| /* |
| * linux/fs/ext3/inode.c |
| * |
| * Copyright (C) 1992, 1993, 1994, 1995 |
| * Remy Card (card@masi.ibp.fr) |
| * Laboratoire MASI - Institut Blaise Pascal |
| * Universite Pierre et Marie Curie (Paris VI) |
| * |
| * from |
| * |
| * linux/fs/minix/inode.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * |
| * Goal-directed block allocation by Stephen Tweedie |
| * (sct@redhat.com), 1993, 1998 |
| * Big-endian to little-endian byte-swapping/bitmaps by |
| * David S. Miller (davem@caip.rutgers.edu), 1995 |
| * 64-bit file support on 64-bit platforms by Jakub Jelinek |
| * (jj@sunsite.ms.mff.cuni.cz) |
| * |
| * Assorted race fixes, rewrite of ext3_get_block() by Al Viro, 2000 |
| */ |
| |
| #include <linux/fs.h> |
| #include <linux/sched.h> |
| #include <linux/ext3_jbd.h> |
| #include <linux/jbd.h> |
| #include <linux/locks.h> |
| #include <linux/smp_lock.h> |
| #include <linux/highuid.h> |
| #include <linux/quotaops.h> |
| #include <linux/module.h> |
| |
| |
| /* |
| * SEARCH_FROM_ZERO forces each block allocation to search from the start |
| * of the filesystem. This is to force rapid reallocation of recently-freed |
| * blocks. The file fragmentation is horrendous. |
| */ |
| #undef SEARCH_FROM_ZERO |
| |
| /* The ext3 forget function must perform a revoke if we are freeing data |
| * which has been journaled. Metadata (eg. indirect blocks) must be |
| * revoked in all cases. |
| * |
| * "bh" may be NULL: a metadata block may have been freed from memory |
| * but there may still be a record of it in the journal, and that record |
| * still needs to be revoked. |
| */ |
| |
| static int ext3_forget(handle_t *handle, int is_metadata, |
| struct inode *inode, struct buffer_head *bh, |
| int blocknr) |
| { |
| int err; |
| |
| BUFFER_TRACE(bh, "enter"); |
| |
| jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, " |
| "data mode %lx\n", |
| bh, is_metadata, inode->i_mode, |
| test_opt(inode->i_sb, DATA_FLAGS)); |
| |
| /* Never use the revoke function if we are doing full data |
| * journaling: there is no need to, and a V1 superblock won't |
| * support it. Otherwise, only skip the revoke on un-journaled |
| * data blocks. */ |
| |
| if (test_opt(inode->i_sb, DATA_FLAGS) == EXT3_MOUNT_JOURNAL_DATA || |
| (!is_metadata && !ext3_should_journal_data(inode))) { |
| if (bh) { |
| BUFFER_TRACE(bh, "call journal_forget"); |
| ext3_journal_forget(handle, bh); |
| } |
| return 0; |
| } |
| |
| /* |
| * data!=journal && (is_metadata || should_journal_data(inode)) |
| */ |
| BUFFER_TRACE(bh, "call ext3_journal_revoke"); |
| err = ext3_journal_revoke(handle, blocknr, bh); |
| if (err) |
| ext3_abort(inode->i_sb, __FUNCTION__, |
| "error %d when attempting revoke", err); |
| BUFFER_TRACE(bh, "exit"); |
| return err; |
| } |
| |
| /* |
| * Truncate transactions can be complex and absolutely huge. So we need to |
| * be able to restart the transaction at a conventient checkpoint to make |
| * sure we don't overflow the journal. |
| * |
| * start_transaction gets us a new handle for a truncate transaction, |
| * and extend_transaction tries to extend the existing one a bit. If |
| * extend fails, we need to propagate the failure up and restart the |
| * transaction in the top-level truncate loop. --sct |
| */ |
| |
| static handle_t *start_transaction(struct inode *inode) |
| { |
| long needed; |
| handle_t *result; |
| |
| needed = inode->i_blocks; |
| if (needed > EXT3_MAX_TRANS_DATA) |
| needed = EXT3_MAX_TRANS_DATA; |
| |
| result = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS + needed); |
| if (!IS_ERR(result)) |
| return result; |
| |
| ext3_std_error(inode->i_sb, PTR_ERR(result)); |
| return result; |
| } |
| |
| /* |
| * Try to extend this transaction for the purposes of truncation. |
| * |
| * Returns 0 if we managed to create more room. If we can't create more |
| * room, and the transaction must be restarted we return 1. |
| */ |
| static int try_to_extend_transaction(handle_t *handle, struct inode *inode) |
| { |
| long needed; |
| |
| if (handle->h_buffer_credits > EXT3_RESERVE_TRANS_BLOCKS) |
| return 0; |
| needed = inode->i_blocks; |
| if (needed > EXT3_MAX_TRANS_DATA) |
| needed = EXT3_MAX_TRANS_DATA; |
| if (!ext3_journal_extend(handle, EXT3_RESERVE_TRANS_BLOCKS + needed)) |
| return 0; |
| return 1; |
| } |
| |
| /* |
| * Restart the transaction associated with *handle. This does a commit, |
| * so before we call here everything must be consistently dirtied against |
| * this transaction. |
| */ |
| static int ext3_journal_test_restart(handle_t *handle, struct inode *inode) |
| { |
| long needed = inode->i_blocks; |
| if (needed > EXT3_MAX_TRANS_DATA) |
| needed = EXT3_MAX_TRANS_DATA; |
| jbd_debug(2, "restarting handle %p\n", handle); |
| return ext3_journal_restart(handle, EXT3_DATA_TRANS_BLOCKS + needed); |
| } |
| |
| /* |
| * Called at each iput() |
| */ |
| void ext3_put_inode (struct inode * inode) |
| { |
| ext3_discard_prealloc (inode); |
| } |
| |
| /* |
| * Called at the last iput() if i_nlink is zero. |
| */ |
| void ext3_delete_inode (struct inode * inode) |
| { |
| handle_t *handle; |
| |
| if (is_bad_inode(inode) || |
| inode->i_ino == EXT3_ACL_IDX_INO || |
| inode->i_ino == EXT3_ACL_DATA_INO) |
| goto no_delete; |
| |
| lock_kernel(); |
| handle = start_transaction(inode); |
| if (IS_ERR(handle)) { |
| /* If we're going to skip the normal cleanup, we still |
| * need to make sure that the in-core orphan linked list |
| * is properly cleaned up. */ |
| ext3_orphan_del(NULL, inode); |
| |
| ext3_std_error(inode->i_sb, PTR_ERR(handle)); |
| unlock_kernel(); |
| goto no_delete; |
| } |
| |
| if (IS_SYNC(inode)) |
| handle->h_sync = 1; |
| inode->i_size = 0; |
| if (inode->i_blocks) |
| ext3_truncate(inode); |
| /* |
| * Kill off the orphan record which ext3_truncate created. |
| * AKPM: I think this can be inside the above `if'. |
| * Note that ext3_orphan_del() has to be able to cope with the |
| * deletion of a non-existent orphan - this is because we don't |
| * know if ext3_truncate() actually created an orphan record. |
| * (Well, we could do this if we need to, but heck - it works) |
| */ |
| ext3_orphan_del(handle, inode); |
| inode->u.ext3_i.i_dtime = CURRENT_TIME; |
| |
| /* |
| * One subtle ordering requirement: if anything has gone wrong |
| * (transaction abort, IO errors, whatever), then we can still |
| * do these next steps (the fs will already have been marked as |
| * having errors), but we can't free the inode if the mark_dirty |
| * fails. |
| */ |
| if (ext3_mark_inode_dirty(handle, inode)) |
| /* If that failed, just do the required in-core inode clear. */ |
| clear_inode(inode); |
| else |
| ext3_free_inode(handle, inode); |
| ext3_journal_stop(handle, inode); |
| unlock_kernel(); |
| return; |
| no_delete: |
| clear_inode(inode); /* We must guarantee clearing of inode... */ |
| } |
| |
| void ext3_discard_prealloc (struct inode * inode) |
| { |
| #ifdef EXT3_PREALLOCATE |
| lock_kernel(); |
| /* Writer: ->i_prealloc* */ |
| if (inode->u.ext3_i.i_prealloc_count) { |
| unsigned short total = inode->u.ext3_i.i_prealloc_count; |
| unsigned long block = inode->u.ext3_i.i_prealloc_block; |
| inode->u.ext3_i.i_prealloc_count = 0; |
| inode->u.ext3_i.i_prealloc_block = 0; |
| /* Writer: end */ |
| ext3_free_blocks (inode, block, total); |
| } |
| unlock_kernel(); |
| #endif |
| } |
| |
| static int ext3_alloc_block (handle_t *handle, |
| struct inode * inode, unsigned long goal, int *err) |
| { |
| #ifdef EXT3FS_DEBUG |
| static unsigned long alloc_hits = 0, alloc_attempts = 0; |
| #endif |
| unsigned long result; |
| |
| #ifdef EXT3_PREALLOCATE |
| /* Writer: ->i_prealloc* */ |
| if (inode->u.ext3_i.i_prealloc_count && |
| (goal == inode->u.ext3_i.i_prealloc_block || |
| goal + 1 == inode->u.ext3_i.i_prealloc_block)) |
| { |
| result = inode->u.ext3_i.i_prealloc_block++; |
| inode->u.ext3_i.i_prealloc_count--; |
| /* Writer: end */ |
| ext3_debug ("preallocation hit (%lu/%lu).\n", |
| ++alloc_hits, ++alloc_attempts); |
| } else { |
| ext3_discard_prealloc (inode); |
| ext3_debug ("preallocation miss (%lu/%lu).\n", |
| alloc_hits, ++alloc_attempts); |
| if (S_ISREG(inode->i_mode)) |
| result = ext3_new_block (inode, goal, |
| &inode->u.ext3_i.i_prealloc_count, |
| &inode->u.ext3_i.i_prealloc_block, err); |
| else |
| result = ext3_new_block (inode, goal, 0, 0, err); |
| /* |
| * AKPM: this is somewhat sticky. I'm not surprised it was |
| * disabled in 2.2's ext3. Need to integrate b_committed_data |
| * guarding with preallocation, if indeed preallocation is |
| * effective. |
| */ |
| } |
| #else |
| result = ext3_new_block (handle, inode, goal, 0, 0, err); |
| #endif |
| return result; |
| } |
| |
| |
| typedef struct { |
| u32 *p; |
| u32 key; |
| struct buffer_head *bh; |
| } Indirect; |
| |
| static inline void add_chain(Indirect *p, struct buffer_head *bh, u32 *v) |
| { |
| p->key = *(p->p = v); |
| p->bh = bh; |
| } |
| |
| static inline int verify_chain(Indirect *from, Indirect *to) |
| { |
| while (from <= to && from->key == *from->p) |
| from++; |
| return (from > to); |
| } |
| |
| /** |
| * ext3_block_to_path - parse the block number into array of offsets |
| * @inode: inode in question (we are only interested in its superblock) |
| * @i_block: block number to be parsed |
| * @offsets: array to store the offsets in |
| * |
| * To store the locations of file's data ext3 uses a data structure common |
| * for UNIX filesystems - tree of pointers anchored in the inode, with |
| * data blocks at leaves and indirect blocks in intermediate nodes. |
| * This function translates the block number into path in that tree - |
| * return value is the path length and @offsets[n] is the offset of |
| * pointer to (n+1)th node in the nth one. If @block is out of range |
| * (negative or too large) warning is printed and zero returned. |
| * |
| * Note: function doesn't find node addresses, so no IO is needed. All |
| * we need to know is the capacity of indirect blocks (taken from the |
| * inode->i_sb). |
| */ |
| |
| /* |
| * Portability note: the last comparison (check that we fit into triple |
| * indirect block) is spelled differently, because otherwise on an |
| * architecture with 32-bit longs and 8Kb pages we might get into trouble |
| * if our filesystem had 8Kb blocks. We might use long long, but that would |
| * kill us on x86. Oh, well, at least the sign propagation does not matter - |
| * i_block would have to be negative in the very beginning, so we would not |
| * get there at all. |
| */ |
| |
| static int ext3_block_to_path(struct inode *inode, long i_block, int offsets[4]) |
| { |
| int ptrs = EXT3_ADDR_PER_BLOCK(inode->i_sb); |
| int ptrs_bits = EXT3_ADDR_PER_BLOCK_BITS(inode->i_sb); |
| const long direct_blocks = EXT3_NDIR_BLOCKS, |
| indirect_blocks = ptrs, |
| double_blocks = (1 << (ptrs_bits * 2)); |
| int n = 0; |
| |
| if (i_block < 0) { |
| ext3_warning (inode->i_sb, "ext3_block_to_path", "block < 0"); |
| } else if (i_block < direct_blocks) { |
| offsets[n++] = i_block; |
| } else if ( (i_block -= direct_blocks) < indirect_blocks) { |
| offsets[n++] = EXT3_IND_BLOCK; |
| offsets[n++] = i_block; |
| } else if ((i_block -= indirect_blocks) < double_blocks) { |
| offsets[n++] = EXT3_DIND_BLOCK; |
| offsets[n++] = i_block >> ptrs_bits; |
| offsets[n++] = i_block & (ptrs - 1); |
| } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) { |
| offsets[n++] = EXT3_TIND_BLOCK; |
| offsets[n++] = i_block >> (ptrs_bits * 2); |
| offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1); |
| offsets[n++] = i_block & (ptrs - 1); |
| } else { |
| ext3_warning (inode->i_sb, "ext3_block_to_path", "block > big"); |
| } |
| return n; |
| } |
| |
| /** |
| * ext3_get_branch - read the chain of indirect blocks leading to data |
| * @inode: inode in question |
| * @depth: depth of the chain (1 - direct pointer, etc.) |
| * @offsets: offsets of pointers in inode/indirect blocks |
| * @chain: place to store the result |
| * @err: here we store the error value |
| * |
| * Function fills the array of triples <key, p, bh> and returns %NULL |
| * if everything went OK or the pointer to the last filled triple |
| * (incomplete one) otherwise. Upon the return chain[i].key contains |
| * the number of (i+1)-th block in the chain (as it is stored in memory, |
| * i.e. little-endian 32-bit), chain[i].p contains the address of that |
| * number (it points into struct inode for i==0 and into the bh->b_data |
| * for i>0) and chain[i].bh points to the buffer_head of i-th indirect |
| * block for i>0 and NULL for i==0. In other words, it holds the block |
| * numbers of the chain, addresses they were taken from (and where we can |
| * verify that chain did not change) and buffer_heads hosting these |
| * numbers. |
| * |
| * Function stops when it stumbles upon zero pointer (absent block) |
| * (pointer to last triple returned, *@err == 0) |
| * or when it gets an IO error reading an indirect block |
| * (ditto, *@err == -EIO) |
| * or when it notices that chain had been changed while it was reading |
| * (ditto, *@err == -EAGAIN) |
| * or when it reads all @depth-1 indirect blocks successfully and finds |
| * the whole chain, all way to the data (returns %NULL, *err == 0). |
| */ |
| static Indirect *ext3_get_branch(struct inode *inode, int depth, int *offsets, |
| Indirect chain[4], int *err) |
| { |
| struct super_block *sb = inode->i_sb; |
| Indirect *p = chain; |
| struct buffer_head *bh; |
| |
| *err = 0; |
| /* i_data is not going away, no lock needed */ |
| add_chain (chain, NULL, inode->u.ext3_i.i_data + *offsets); |
| if (!p->key) |
| goto no_block; |
| while (--depth) { |
| bh = sb_bread(sb, le32_to_cpu(p->key)); |
| if (!bh) |
| goto failure; |
| /* Reader: pointers */ |
| if (!verify_chain(chain, p)) |
| goto changed; |
| add_chain(++p, bh, (u32*)bh->b_data + *++offsets); |
| /* Reader: end */ |
| if (!p->key) |
| goto no_block; |
| } |
| return NULL; |
| |
| changed: |
| *err = -EAGAIN; |
| goto no_block; |
| failure: |
| *err = -EIO; |
| no_block: |
| return p; |
| } |
| |
| /** |
| * ext3_find_near - find a place for allocation with sufficient locality |
| * @inode: owner |
| * @ind: descriptor of indirect block. |
| * |
| * This function returns the prefered place for block allocation. |
| * It is used when heuristic for sequential allocation fails. |
| * Rules are: |
| * + if there is a block to the left of our position - allocate near it. |
| * + if pointer will live in indirect block - allocate near that block. |
| * + if pointer will live in inode - allocate in the same |
| * cylinder group. |
| * Caller must make sure that @ind is valid and will stay that way. |
| */ |
| |
| static inline unsigned long ext3_find_near(struct inode *inode, Indirect *ind) |
| { |
| u32 *start = ind->bh ? (u32*) ind->bh->b_data : inode->u.ext3_i.i_data; |
| u32 *p; |
| |
| /* Try to find previous block */ |
| for (p = ind->p - 1; p >= start; p--) |
| if (*p) |
| return le32_to_cpu(*p); |
| |
| /* No such thing, so let's try location of indirect block */ |
| if (ind->bh) |
| return ind->bh->b_blocknr; |
| |
| /* |
| * It is going to be refered from inode itself? OK, just put it into |
| * the same cylinder group then. |
| */ |
| return (inode->u.ext3_i.i_block_group * |
| EXT3_BLOCKS_PER_GROUP(inode->i_sb)) + |
| le32_to_cpu(inode->i_sb->u.ext3_sb.s_es->s_first_data_block); |
| } |
| |
| /** |
| * ext3_find_goal - find a prefered place for allocation. |
| * @inode: owner |
| * @block: block we want |
| * @chain: chain of indirect blocks |
| * @partial: pointer to the last triple within a chain |
| * @goal: place to store the result. |
| * |
| * Normally this function find the prefered place for block allocation, |
| * stores it in *@goal and returns zero. If the branch had been changed |
| * under us we return -EAGAIN. |
| */ |
| |
| static int ext3_find_goal(struct inode *inode, long block, Indirect chain[4], |
| Indirect *partial, unsigned long *goal) |
| { |
| /* Writer: ->i_next_alloc* */ |
| if (block == inode->u.ext3_i.i_next_alloc_block + 1) { |
| inode->u.ext3_i.i_next_alloc_block++; |
| inode->u.ext3_i.i_next_alloc_goal++; |
| } |
| #ifdef SEARCH_FROM_ZERO |
| inode->u.ext3_i.i_next_alloc_block = 0; |
| inode->u.ext3_i.i_next_alloc_goal = 0; |
| #endif |
| /* Writer: end */ |
| /* Reader: pointers, ->i_next_alloc* */ |
| if (verify_chain(chain, partial)) { |
| /* |
| * try the heuristic for sequential allocation, |
| * failing that at least try to get decent locality. |
| */ |
| if (block == inode->u.ext3_i.i_next_alloc_block) |
| *goal = inode->u.ext3_i.i_next_alloc_goal; |
| if (!*goal) |
| *goal = ext3_find_near(inode, partial); |
| #ifdef SEARCH_FROM_ZERO |
| *goal = 0; |
| #endif |
| return 0; |
| } |
| /* Reader: end */ |
| return -EAGAIN; |
| } |
| |
| /** |
| * ext3_alloc_branch - allocate and set up a chain of blocks. |
| * @inode: owner |
| * @num: depth of the chain (number of blocks to allocate) |
| * @offsets: offsets (in the blocks) to store the pointers to next. |
| * @branch: place to store the chain in. |
| * |
| * This function allocates @num blocks, zeroes out all but the last one, |
| * links them into chain and (if we are synchronous) writes them to disk. |
| * In other words, it prepares a branch that can be spliced onto the |
| * inode. It stores the information about that chain in the branch[], in |
| * the same format as ext3_get_branch() would do. We are calling it after |
| * we had read the existing part of chain and partial points to the last |
| * triple of that (one with zero ->key). Upon the exit we have the same |
| * picture as after the successful ext3_get_block(), excpet that in one |
| * place chain is disconnected - *branch->p is still zero (we did not |
| * set the last link), but branch->key contains the number that should |
| * be placed into *branch->p to fill that gap. |
| * |
| * If allocation fails we free all blocks we've allocated (and forget |
| * their buffer_heads) and return the error value the from failed |
| * ext3_alloc_block() (normally -ENOSPC). Otherwise we set the chain |
| * as described above and return 0. |
| */ |
| |
| static int ext3_alloc_branch(handle_t *handle, struct inode *inode, |
| int num, |
| unsigned long goal, |
| int *offsets, |
| Indirect *branch) |
| { |
| int blocksize = inode->i_sb->s_blocksize; |
| int n = 0, keys = 0; |
| int err = 0; |
| int i; |
| int parent = ext3_alloc_block(handle, inode, goal, &err); |
| |
| branch[0].key = cpu_to_le32(parent); |
| if (parent) { |
| for (n = 1; n < num; n++) { |
| struct buffer_head *bh; |
| /* Allocate the next block */ |
| int nr = ext3_alloc_block(handle, inode, parent, &err); |
| if (!nr) |
| break; |
| branch[n].key = cpu_to_le32(nr); |
| keys = n+1; |
| |
| /* |
| * Get buffer_head for parent block, zero it out |
| * and set the pointer to new one, then send |
| * parent to disk. |
| */ |
| bh = sb_getblk(inode->i_sb, parent); |
| branch[n].bh = bh; |
| lock_buffer(bh); |
| BUFFER_TRACE(bh, "call get_create_access"); |
| err = ext3_journal_get_create_access(handle, bh); |
| if (err) { |
| unlock_buffer(bh); |
| brelse(bh); |
| break; |
| } |
| |
| memset(bh->b_data, 0, blocksize); |
| branch[n].p = (u32*) bh->b_data + offsets[n]; |
| *branch[n].p = branch[n].key; |
| BUFFER_TRACE(bh, "marking uptodate"); |
| mark_buffer_uptodate(bh, 1); |
| unlock_buffer(bh); |
| |
| BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata"); |
| err = ext3_journal_dirty_metadata(handle, bh); |
| if (err) |
| break; |
| |
| parent = nr; |
| } |
| if (IS_SYNC(inode)) |
| handle->h_sync = 1; |
| } |
| if (n == num) |
| return 0; |
| |
| /* Allocation failed, free what we already allocated */ |
| for (i = 1; i < keys; i++) { |
| BUFFER_TRACE(branch[i].bh, "call journal_forget"); |
| ext3_journal_forget(handle, branch[i].bh); |
| } |
| for (i = 0; i < keys; i++) |
| ext3_free_blocks(handle, inode, le32_to_cpu(branch[i].key), 1); |
| return err; |
| } |
| |
| /** |
| * ext3_splice_branch - splice the allocated branch onto inode. |
| * @inode: owner |
| * @block: (logical) number of block we are adding |
| * @chain: chain of indirect blocks (with a missing link - see |
| * ext3_alloc_branch) |
| * @where: location of missing link |
| * @num: number of blocks we are adding |
| * |
| * This function verifies that chain (up to the missing link) had not |
| * changed, fills the missing link and does all housekeeping needed in |
| * inode (->i_blocks, etc.). In case of success we end up with the full |
| * chain to new block and return 0. Otherwise (== chain had been changed) |
| * we free the new blocks (forgetting their buffer_heads, indeed) and |
| * return -EAGAIN. |
| */ |
| |
| static int ext3_splice_branch(handle_t *handle, struct inode *inode, long block, |
| Indirect chain[4], Indirect *where, int num) |
| { |
| int i; |
| int err = 0; |
| |
| /* |
| * If we're splicing into a [td]indirect block (as opposed to the |
| * inode) then we need to get write access to the [td]indirect block |
| * before the splice. |
| */ |
| if (where->bh) { |
| BUFFER_TRACE(where->bh, "get_write_access"); |
| err = ext3_journal_get_write_access(handle, where->bh); |
| if (err) |
| goto err_out; |
| } |
| /* Verify that place we are splicing to is still there and vacant */ |
| |
| /* Writer: pointers, ->i_next_alloc* */ |
| if (!verify_chain(chain, where-1) || *where->p) |
| /* Writer: end */ |
| goto changed; |
| |
| /* That's it */ |
| |
| *where->p = where->key; |
| inode->u.ext3_i.i_next_alloc_block = block; |
| inode->u.ext3_i.i_next_alloc_goal = le32_to_cpu(where[num-1].key); |
| #ifdef SEARCH_FROM_ZERO |
| inode->u.ext3_i.i_next_alloc_block = 0; |
| inode->u.ext3_i.i_next_alloc_goal = 0; |
| #endif |
| /* Writer: end */ |
| |
| /* We are done with atomic stuff, now do the rest of housekeeping */ |
| |
| inode->i_ctime = CURRENT_TIME; |
| ext3_mark_inode_dirty(handle, inode); |
| |
| /* had we spliced it onto indirect block? */ |
| if (where->bh) { |
| /* |
| * akpm: If we spliced it onto an indirect block, we haven't |
| * altered the inode. Note however that if it is being spliced |
| * onto an indirect block at the very end of the file (the |
| * file is growing) then we *will* alter the inode to reflect |
| * the new i_size. But that is not done here - it is done in |
| * generic_commit_write->__mark_inode_dirty->ext3_dirty_inode. |
| */ |
| jbd_debug(5, "splicing indirect only\n"); |
| BUFFER_TRACE(where->bh, "call ext3_journal_dirty_metadata"); |
| err = ext3_journal_dirty_metadata(handle, where->bh); |
| if (err) |
| goto err_out; |
| } else { |
| /* |
| * OK, we spliced it into the inode itself on a direct block. |
| * Inode was dirtied above. |
| */ |
| jbd_debug(5, "splicing direct\n"); |
| } |
| return err; |
| |
| changed: |
| /* |
| * AKPM: if where[i].bh isn't part of the current updating |
| * transaction then we explode nastily. Test this code path. |
| */ |
| jbd_debug(1, "the chain changed: try again\n"); |
| err = -EAGAIN; |
| |
| err_out: |
| for (i = 1; i < num; i++) { |
| BUFFER_TRACE(where[i].bh, "call journal_forget"); |
| ext3_journal_forget(handle, where[i].bh); |
| } |
| /* For the normal collision cleanup case, we free up the blocks. |
| * On genuine filesystem errors we don't even think about doing |
| * that. */ |
| if (err == -EAGAIN) |
| for (i = 0; i < num; i++) |
| ext3_free_blocks(handle, inode, |
| le32_to_cpu(where[i].key), 1); |
| return err; |
| } |
| |
| /* |
| * Allocation strategy is simple: if we have to allocate something, we will |
| * have to go the whole way to leaf. So let's do it before attaching anything |
| * to tree, set linkage between the newborn blocks, write them if sync is |
| * required, recheck the path, free and repeat if check fails, otherwise |
| * set the last missing link (that will protect us from any truncate-generated |
| * removals - all blocks on the path are immune now) and possibly force the |
| * write on the parent block. |
| * That has a nice additional property: no special recovery from the failed |
| * allocations is needed - we simply release blocks and do not touch anything |
| * reachable from inode. |
| * |
| * akpm: `handle' can be NULL if create == 0. |
| */ |
| |
| static int ext3_get_block_handle(handle_t *handle, struct inode *inode, |
| sector_t iblock, |
| struct buffer_head *bh_result, int create) |
| { |
| int err = -EIO; |
| int offsets[4]; |
| Indirect chain[4]; |
| Indirect *partial; |
| unsigned long goal; |
| int left; |
| int depth = ext3_block_to_path(inode, iblock, offsets); |
| loff_t new_size; |
| |
| J_ASSERT(handle != NULL || create == 0); |
| |
| if (depth == 0) |
| goto out; |
| |
| lock_kernel(); |
| reread: |
| partial = ext3_get_branch(inode, depth, offsets, chain, &err); |
| |
| /* Simplest case - block found, no allocation needed */ |
| if (!partial) { |
| bh_result->b_state &= ~(1UL << BH_New); |
| got_it: |
| bh_result->b_dev = inode->i_dev; |
| bh_result->b_blocknr = le32_to_cpu(chain[depth-1].key); |
| bh_result->b_state |= (1UL << BH_Mapped); |
| /* Clean up and exit */ |
| partial = chain+depth-1; /* the whole chain */ |
| goto cleanup; |
| } |
| |
| /* Next simple case - plain lookup or failed read of indirect block */ |
| if (!create || err == -EIO) { |
| cleanup: |
| while (partial > chain) { |
| BUFFER_TRACE(partial->bh, "call brelse"); |
| brelse(partial->bh); |
| partial--; |
| } |
| BUFFER_TRACE(bh_result, "returned"); |
| unlock_kernel(); |
| out: |
| return err; |
| } |
| |
| /* |
| * Indirect block might be removed by truncate while we were |
| * reading it. Handling of that case (forget what we've got and |
| * reread) is taken out of the main path. |
| */ |
| if (err == -EAGAIN) |
| goto changed; |
| |
| if (ext3_find_goal(inode, iblock, chain, partial, &goal) < 0) |
| goto changed; |
| |
| left = (chain + depth) - partial; |
| |
| /* |
| * Block out ext3_truncate while we alter the tree |
| */ |
| down_read(&inode->u.ext3_i.truncate_sem); |
| err = ext3_alloc_branch(handle, inode, left, goal, |
| offsets+(partial-chain), partial); |
| |
| /* The ext3_splice_branch call will free and forget any buffers |
| * on the new chain if there is a failure, but that risks using |
| * up transaction credits, especially for bitmaps where the |
| * credits cannot be returned. Can we handle this somehow? We |
| * may need to return -EAGAIN upwards in the worst case. --sct */ |
| if (!err) |
| err = ext3_splice_branch(handle, inode, iblock, chain, |
| partial, left); |
| up_read(&inode->u.ext3_i.truncate_sem); |
| if (err == -EAGAIN) |
| goto changed; |
| if (err) |
| goto cleanup; |
| |
| new_size = inode->i_size; |
| /* |
| * This is not racy against ext3_truncate's modification of i_disksize |
| * because VM/VFS ensures that the file cannot be extended while |
| * truncate is in progress. It is racy between multiple parallel |
| * instances of get_block, but we have the BKL. |
| */ |
| if (new_size > inode->u.ext3_i.i_disksize) |
| inode->u.ext3_i.i_disksize = new_size; |
| |
| bh_result->b_state |= (1UL << BH_New); |
| goto got_it; |
| |
| changed: |
| while (partial > chain) { |
| jbd_debug(1, "buffer chain changed, retrying\n"); |
| BUFFER_TRACE(partial->bh, "brelsing"); |
| brelse(partial->bh); |
| partial--; |
| } |
| goto reread; |
| } |
| |
| static int ext3_get_block(struct inode *inode, sector_t iblock, |
| struct buffer_head *bh_result, int create) |
| { |
| handle_t *handle = 0; |
| int ret; |
| |
| if (create) { |
| handle = ext3_journal_current_handle(); |
| J_ASSERT(handle != 0); |
| } |
| ret = ext3_get_block_handle(handle, inode, iblock, bh_result, create); |
| return ret; |
| } |
| |
| /* |
| * `handle' can be NULL if create is zero |
| */ |
| struct buffer_head *ext3_getblk(handle_t *handle, struct inode * inode, |
| long block, int create, int * errp) |
| { |
| struct buffer_head dummy; |
| int fatal = 0, err; |
| |
| J_ASSERT(handle != NULL || create == 0); |
| |
| dummy.b_state = 0; |
| dummy.b_blocknr = -1000; |
| buffer_trace_init(&dummy.b_history); |
| *errp = ext3_get_block_handle(handle, inode, block, &dummy, create); |
| if (!*errp && buffer_mapped(&dummy)) { |
| struct buffer_head *bh; |
| bh = sb_getblk(inode->i_sb, dummy.b_blocknr); |
| if (buffer_new(&dummy)) { |
| J_ASSERT(create != 0); |
| J_ASSERT(handle != 0); |
| |
| /* Now that we do not always journal data, we |
| should keep in mind whether this should |
| always journal the new buffer as metadata. |
| For now, regular file writes use |
| ext3_get_block instead, so it's not a |
| problem. */ |
| lock_kernel(); |
| lock_buffer(bh); |
| BUFFER_TRACE(bh, "call get_create_access"); |
| fatal = ext3_journal_get_create_access(handle, bh); |
| if (!fatal) { |
| memset(bh->b_data, 0, |
| inode->i_sb->s_blocksize); |
| mark_buffer_uptodate(bh, 1); |
| } |
| unlock_buffer(bh); |
| BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata"); |
| err = ext3_journal_dirty_metadata(handle, bh); |
| if (!fatal) fatal = err; |
| unlock_kernel(); |
| } else { |
| BUFFER_TRACE(bh, "not a new buffer"); |
| } |
| if (fatal) { |
| *errp = fatal; |
| brelse(bh); |
| bh = NULL; |
| } |
| return bh; |
| } |
| return NULL; |
| } |
| |
| struct buffer_head *ext3_bread(handle_t *handle, struct inode * inode, |
| int block, int create, int *err) |
| { |
| struct buffer_head * bh; |
| int prev_blocks; |
| |
| prev_blocks = inode->i_blocks; |
| |
| bh = ext3_getblk (handle, inode, block, create, err); |
| if (!bh) |
| return bh; |
| #ifdef EXT3_PREALLOCATE |
| /* |
| * If the inode has grown, and this is a directory, then use a few |
| * more of the preallocated blocks to keep directory fragmentation |
| * down. The preallocated blocks are guaranteed to be contiguous. |
| */ |
| if (create && |
| S_ISDIR(inode->i_mode) && |
| inode->i_blocks > prev_blocks && |
| EXT3_HAS_COMPAT_FEATURE(inode->i_sb, |
| EXT3_FEATURE_COMPAT_DIR_PREALLOC)) { |
| int i; |
| struct buffer_head *tmp_bh; |
| |
| for (i = 1; |
| inode->u.ext3_i.i_prealloc_count && |
| i < EXT3_SB(inode->i_sb)->s_es->s_prealloc_dir_blocks; |
| i++) { |
| /* |
| * ext3_getblk will zero out the contents of the |
| * directory for us |
| */ |
| tmp_bh = ext3_getblk(handle, inode, |
| block+i, create, err); |
| if (!tmp_bh) { |
| brelse (bh); |
| return 0; |
| } |
| brelse (tmp_bh); |
| } |
| } |
| #endif |
| if (buffer_uptodate(bh)) |
| return bh; |
| ll_rw_block (READ, 1, &bh); |
| wait_on_buffer (bh); |
| if (buffer_uptodate(bh)) |
| return bh; |
| brelse (bh); |
| *err = -EIO; |
| return NULL; |
| } |
| |
| static int walk_page_buffers( handle_t *handle, |
| struct buffer_head *head, |
| unsigned from, |
| unsigned to, |
| int *partial, |
| int (*fn)( handle_t *handle, |
| struct buffer_head *bh)) |
| { |
| struct buffer_head *bh; |
| unsigned block_start, block_end; |
| unsigned blocksize = head->b_size; |
| int err, ret = 0; |
| |
| for ( bh = head, block_start = 0; |
| ret == 0 && (bh != head || !block_start); |
| block_start = block_end, bh = bh->b_this_page) |
| { |
| block_end = block_start + blocksize; |
| if (block_end <= from || block_start >= to) { |
| if (partial && !buffer_uptodate(bh)) |
| *partial = 1; |
| continue; |
| } |
| err = (*fn)(handle, bh); |
| if (!ret) |
| ret = err; |
| } |
| return ret; |
| } |
| |
| /* |
| * To preserve ordering, it is essential that the hole instantiation and |
| * the data write be encapsulated in a single transaction. We cannot |
| * close off a transaction and start a new one between the ext3_get_block() |
| * and the commit_write(). So doing the journal_start at the start of |
| * prepare_write() is the right place. |
| * |
| * Also, this function can nest inside ext3_writepage() -> |
| * block_write_full_page(). In that case, we *know* that ext3_writepage() |
| * has generated enough buffer credits to do the whole page. So we won't |
| * block on the journal in that case, which is good, because the caller may |
| * be PF_MEMALLOC. |
| * |
| * By accident, ext3 can be reentered when a transaction is open via |
| * quota file writes. If we were to commit the transaction while thus |
| * reentered, there can be a deadlock - we would be holding a quota |
| * lock, and the commit would never complete if another thread had a |
| * transaction open and was blocking on the quota lock - a ranking |
| * violation. |
| * |
| * So what we do is to rely on the fact that journal_stop/journal_start |
| * will _not_ run commit under these circumstances because handle->h_ref |
| * is elevated. We'll still have enough credits for the tiny quotafile |
| * write. |
| */ |
| |
| static int do_journal_get_write_access(handle_t *handle, |
| struct buffer_head *bh) |
| { |
| return ext3_journal_get_write_access(handle, bh); |
| } |
| |
| static int ext3_prepare_write(struct file *file, struct page *page, |
| unsigned from, unsigned to) |
| { |
| struct inode *inode = page->mapping->host; |
| handle_t *handle = ext3_journal_current_handle(); |
| int ret, needed_blocks = ext3_writepage_trans_blocks(inode); |
| |
| lock_kernel(); |
| handle = ext3_journal_start(inode, needed_blocks); |
| if (IS_ERR(handle)) { |
| ret = PTR_ERR(handle); |
| goto out; |
| } |
| ret = block_prepare_write(page, from, to, ext3_get_block); |
| if (ret != 0) |
| goto prepare_write_failed; |
| |
| if (ext3_should_journal_data(inode)) |
| ret = walk_page_buffers(handle, page->buffers, |
| from, to, NULL, do_journal_get_write_access); |
| prepare_write_failed: |
| if (ret) |
| ext3_journal_stop(handle, inode); |
| out: |
| unlock_kernel(); |
| return ret; |
| } |
| |
| static int journal_dirty_sync_data(handle_t *handle, struct buffer_head *bh) |
| { |
| return ext3_journal_dirty_data(handle, bh, 0); |
| } |
| |
| /* |
| * For ext3_writepage(). We also brelse() the buffer to account for |
| * the bget() which ext3_writepage() performs. |
| */ |
| static int journal_dirty_async_data(handle_t *handle, struct buffer_head *bh) |
| { |
| int ret = ext3_journal_dirty_data(handle, bh, 1); |
| __brelse(bh); |
| return ret; |
| } |
| |
| /* For commit_write() in data=journal mode */ |
| static int commit_write_fn(handle_t *handle, struct buffer_head *bh) |
| { |
| set_bit(BH_Uptodate, &bh->b_state); |
| return ext3_journal_dirty_metadata(handle, bh); |
| } |
| |
| /* |
| * We need to pick up the new inode size which generic_commit_write gave us |
| * `file' can be NULL - eg, when called from block_symlink(). |
| * |
| * ext3 inode->i_dirty_buffers policy: If we're journalling data we |
| * definitely don't want them to appear on the inode at all - instead |
| * we need to manage them at the JBD layer and we need to intercept |
| * the relevant sync operations and translate them into journal operations. |
| * |
| * If we're not journalling data then we can just leave the buffers |
| * on ->i_dirty_buffers. If someone writes them out for us then thanks. |
| * Otherwise we'll do it in commit, if we're using ordered data. |
| */ |
| |
| static int ext3_commit_write(struct file *file, struct page *page, |
| unsigned from, unsigned to) |
| { |
| handle_t *handle = ext3_journal_current_handle(); |
| struct inode *inode = page->mapping->host; |
| int ret = 0, ret2; |
| |
| lock_kernel(); |
| if (ext3_should_journal_data(inode)) { |
| /* |
| * Here we duplicate the generic_commit_write() functionality |
| */ |
| int partial = 0; |
| loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; |
| |
| ret = walk_page_buffers(handle, page->buffers, |
| from, to, &partial, commit_write_fn); |
| if (!partial) |
| SetPageUptodate(page); |
| kunmap(page); |
| if (pos > inode->i_size) |
| inode->i_size = pos; |
| set_bit(EXT3_STATE_JDATA, &inode->u.ext3_i.i_state); |
| } else { |
| if (ext3_should_order_data(inode)) { |
| ret = walk_page_buffers(handle, page->buffers, |
| from, to, NULL, journal_dirty_sync_data); |
| } |
| /* Be careful here if generic_commit_write becomes a |
| * required invocation after block_prepare_write. */ |
| if (ret == 0) |
| ret = generic_commit_write(file, page, from, to); |
| } |
| if (inode->i_size > inode->u.ext3_i.i_disksize) { |
| inode->u.ext3_i.i_disksize = inode->i_size; |
| ret2 = ext3_mark_inode_dirty(handle, inode); |
| if (!ret) |
| ret = ret2; |
| } |
| ret2 = ext3_journal_stop(handle, inode); |
| unlock_kernel(); |
| if (!ret) |
| ret = ret2; |
| return ret; |
| } |
| |
| /* |
| * bmap() is special. It gets used by applications such as lilo and by |
| * the swapper to find the on-disk block of a specific piece of data. |
| * |
| * Naturally, this is dangerous if the block concerned is still in the |
| * journal. If somebody makes a swapfile on an ext3 data-journaling |
| * filesystem and enables swap, then they may get a nasty shock when the |
| * data getting swapped to that swapfile suddenly gets overwritten by |
| * the original zero's written out previously to the journal and |
| * awaiting writeback in the kernel's buffer cache. |
| * |
| * So, if we see any bmap calls here on a modified, data-journaled file, |
| * take extra steps to flush any blocks which might be in the cache. |
| */ |
| static int ext3_bmap(struct address_space *mapping, long block) |
| { |
| struct inode *inode = mapping->host; |
| journal_t *journal; |
| int err; |
| |
| if (test_and_clear_bit(EXT3_STATE_JDATA, &inode->u.ext3_i.i_state)) { |
| /* |
| * This is a REALLY heavyweight approach, but the use of |
| * bmap on dirty files is expected to be extremely rare: |
| * only if we run lilo or swapon on a freshly made file |
| * do we expect this to happen. |
| * |
| * (bmap requires CAP_SYS_RAWIO so this does not |
| * represent an unprivileged user DOS attack --- we'd be |
| * in trouble if mortal users could trigger this path at |
| * will.) |
| * |
| * NB. EXT3_STATE_JDATA is not set on files other than |
| * regular files. If somebody wants to bmap a directory |
| * or symlink and gets confused because the buffer |
| * hasn't yet been flushed to disk, they deserve |
| * everything they get. |
| */ |
| |
| journal = EXT3_JOURNAL(inode); |
| journal_lock_updates(journal); |
| err = journal_flush(journal); |
| journal_unlock_updates(journal); |
| |
| if (err) |
| return 0; |
| } |
| |
| return generic_block_bmap(mapping,block,ext3_get_block); |
| } |
| |
| static int bget_one(handle_t *handle, struct buffer_head *bh) |
| { |
| atomic_inc(&bh->b_count); |
| return 0; |
| } |
| |
| /* |
| * Note that we always start a transaction even if we're not journalling |
| * data. This is to preserve ordering: any hole instantiation within |
| * __block_write_full_page -> ext3_get_block() should be journalled |
| * along with the data so we don't crash and then get metadata which |
| * refers to old data. |
| * |
| * In all journalling modes block_write_full_page() will start the I/O. |
| * |
| * Problem: |
| * |
| * ext3_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() -> |
| * ext3_writepage() |
| * |
| * Similar for: |
| * |
| * ext3_file_write() -> generic_file_write() -> __alloc_pages() -> ... |
| * |
| * Same applies to ext3_get_block(). We will deadlock on various things like |
| * lock_journal and i_truncate_sem. |
| * |
| * Setting PF_MEMALLOC here doesn't work - too many internal memory |
| * allocations fail. |
| * |
| * 16May01: If we're reentered then journal_current_handle() will be |
| * non-zero. We simply *return*. |
| * |
| * 1 July 2001: @@@ FIXME: |
| * In journalled data mode, a data buffer may be metadata against the |
| * current transaction. But the same file is part of a shared mapping |
| * and someone does a writepage() on it. |
| * |
| * We will move the buffer onto the async_data list, but *after* it has |
| * been dirtied. So there's a small window where we have dirty data on |
| * BJ_Metadata. |
| * |
| * Note that this only applies to the last partial page in the file. The |
| * bit which block_write_full_page() uses prepare/commit for. (That's |
| * broken code anyway: it's wrong for msync()). |
| * |
| * It's a rare case: affects the final partial page, for journalled data |
| * where the file is subject to bith write() and writepage() in the same |
| * transction. To fix it we'll need a custom block_write_full_page(). |
| * We'll probably need that anyway for journalling writepage() output. |
| * |
| * We don't honour synchronous mounts for writepage(). That would be |
| * disastrous. Any write() or metadata operation will sync the fs for |
| * us. |
| */ |
| static int ext3_writepage(struct page *page) |
| { |
| struct inode *inode = page->mapping->host; |
| struct buffer_head *page_buffers; |
| handle_t *handle = NULL; |
| int ret = 0, err; |
| int needed; |
| int order_data; |
| |
| J_ASSERT(PageLocked(page)); |
| |
| /* |
| * We give up here if we're reentered, because it might be |
| * for a different filesystem. One *could* look for a |
| * nested transaction opportunity. |
| */ |
| lock_kernel(); |
| if (ext3_journal_current_handle()) |
| goto out_fail; |
| |
| needed = ext3_writepage_trans_blocks(inode); |
| if (current->flags & PF_MEMALLOC) |
| handle = ext3_journal_try_start(inode, needed); |
| else |
| handle = ext3_journal_start(inode, needed); |
| |
| if (IS_ERR(handle)) { |
| ret = PTR_ERR(handle); |
| goto out_fail; |
| } |
| |
| order_data = ext3_should_order_data(inode) || |
| ext3_should_journal_data(inode); |
| |
| unlock_kernel(); |
| |
| page_buffers = NULL; /* Purely to prevent compiler warning */ |
| |
| /* bget() all the buffers */ |
| if (order_data) { |
| if (!page->buffers) |
| create_empty_buffers(page, |
| inode->i_dev, inode->i_sb->s_blocksize); |
| page_buffers = page->buffers; |
| walk_page_buffers(handle, page_buffers, 0, |
| PAGE_CACHE_SIZE, NULL, bget_one); |
| } |
| |
| ret = block_write_full_page(page, ext3_get_block); |
| |
| /* |
| * The page can become unlocked at any point now, and |
| * truncate can then come in and change things. So we |
| * can't touch *page from now on. But *page_buffers is |
| * safe due to elevated refcount. |
| */ |
| |
| handle = ext3_journal_current_handle(); |
| lock_kernel(); |
| |
| /* And attach them to the current transaction */ |
| if (order_data) { |
| err = walk_page_buffers(handle, page_buffers, |
| 0, PAGE_CACHE_SIZE, NULL, journal_dirty_async_data); |
| if (!ret) |
| ret = err; |
| } |
| |
| err = ext3_journal_stop(handle, inode); |
| if (!ret) |
| ret = err; |
| unlock_kernel(); |
| return ret; |
| |
| out_fail: |
| |
| unlock_kernel(); |
| SetPageDirty(page); |
| UnlockPage(page); |
| return ret; |
| } |
| |
| static int ext3_readpage(struct file *file, struct page *page) |
| { |
| return block_read_full_page(page,ext3_get_block); |
| } |
| |
| |
| static int ext3_flushpage(struct page *page, unsigned long offset) |
| { |
| journal_t *journal = EXT3_JOURNAL(page->mapping->host); |
| return journal_flushpage(journal, page, offset); |
| } |
| |
| static int ext3_releasepage(struct page *page, int wait) |
| { |
| journal_t *journal = EXT3_JOURNAL(page->mapping->host); |
| return journal_try_to_free_buffers(journal, page, wait); |
| } |
| |
| |
| struct address_space_operations ext3_aops = { |
| readpage: ext3_readpage, /* BKL not held. Don't need */ |
| writepage: ext3_writepage, /* BKL not held. We take it */ |
| sync_page: block_sync_page, |
| prepare_write: ext3_prepare_write, /* BKL not held. We take it */ |
| commit_write: ext3_commit_write, /* BKL not held. We take it */ |
| bmap: ext3_bmap, /* BKL held */ |
| flushpage: ext3_flushpage, /* BKL not held. Don't need */ |
| releasepage: ext3_releasepage, /* BKL not held. Don't need */ |
| }; |
| |
| /* |
| * ext3_block_truncate_page() zeroes out a mapping from file offset `from' |
| * up to the end of the block which corresponds to `from'. |
| * This required during truncate. We need to physically zero the tail end |
| * of that block so it doesn't yield old data if the file is later grown. |
| */ |
| static int ext3_block_truncate_page(handle_t *handle, |
| struct address_space *mapping, loff_t from) |
| { |
| unsigned long index = from >> PAGE_CACHE_SHIFT; |
| unsigned offset = from & (PAGE_CACHE_SIZE-1); |
| unsigned blocksize, iblock, length, pos; |
| struct inode *inode = mapping->host; |
| struct page *page; |
| struct buffer_head *bh; |
| int err; |
| |
| blocksize = inode->i_sb->s_blocksize; |
| length = offset & (blocksize - 1); |
| |
| /* Block boundary? Nothing to do */ |
| if (!length) |
| return 0; |
| |
| length = blocksize - length; |
| iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits); |
| |
| page = grab_cache_page(mapping, index); |
| err = -ENOMEM; |
| if (!page) |
| goto out; |
| |
| if (!page->buffers) |
| create_empty_buffers(page, inode->i_dev, blocksize); |
| |
| /* Find the buffer that contains "offset" */ |
| bh = page->buffers; |
| pos = blocksize; |
| while (offset >= pos) { |
| bh = bh->b_this_page; |
| iblock++; |
| pos += blocksize; |
| } |
| |
| err = 0; |
| if (!buffer_mapped(bh)) { |
| /* Hole? Nothing to do */ |
| if (buffer_uptodate(bh)) |
| goto unlock; |
| ext3_get_block(inode, iblock, bh, 0); |
| /* Still unmapped? Nothing to do */ |
| if (!buffer_mapped(bh)) |
| goto unlock; |
| } |
| |
| /* Ok, it's mapped. Make sure it's up-to-date */ |
| if (Page_Uptodate(page)) |
| set_bit(BH_Uptodate, &bh->b_state); |
| |
| if (!buffer_uptodate(bh)) { |
| err = -EIO; |
| ll_rw_block(READ, 1, &bh); |
| wait_on_buffer(bh); |
| /* Uhhuh. Read error. Complain and punt. */ |
| if (!buffer_uptodate(bh)) |
| goto unlock; |
| } |
| |
| if (ext3_should_journal_data(inode)) { |
| BUFFER_TRACE(bh, "get write access"); |
| err = ext3_journal_get_write_access(handle, bh); |
| if (err) |
| goto unlock; |
| } |
| |
| memset(kmap(page) + offset, 0, length); |
| flush_dcache_page(page); |
| kunmap(page); |
| |
| BUFFER_TRACE(bh, "zeroed end of block"); |
| |
| err = 0; |
| if (ext3_should_journal_data(inode)) { |
| err = ext3_journal_dirty_metadata(handle, bh); |
| } else { |
| if (ext3_should_order_data(inode)) |
| err = ext3_journal_dirty_data(handle, bh, 0); |
| __mark_buffer_dirty(bh); |
| } |
| |
| unlock: |
| UnlockPage(page); |
| page_cache_release(page); |
| out: |
| return err; |
| } |
| |
| /* |
| * Probably it should be a library function... search for first non-zero word |
| * or memcmp with zero_page, whatever is better for particular architecture. |
| * Linus? |
| */ |
| static inline int all_zeroes(u32 *p, u32 *q) |
| { |
| while (p < q) |
| if (*p++) |
| return 0; |
| return 1; |
| } |
| |
| /** |
| * ext3_find_shared - find the indirect blocks for partial truncation. |
| * @inode: inode in question |
| * @depth: depth of the affected branch |
| * @offsets: offsets of pointers in that branch (see ext3_block_to_path) |
| * @chain: place to store the pointers to partial indirect blocks |
| * @top: place to the (detached) top of branch |
| * |
| * This is a helper function used by ext3_truncate(). |
| * |
| * When we do truncate() we may have to clean the ends of several |
| * indirect blocks but leave the blocks themselves alive. Block is |
| * partially truncated if some data below the new i_size is refered |
| * from it (and it is on the path to the first completely truncated |
| * data block, indeed). We have to free the top of that path along |
| * with everything to the right of the path. Since no allocation |
| * past the truncation point is possible until ext3_truncate() |
| * finishes, we may safely do the latter, but top of branch may |
| * require special attention - pageout below the truncation point |
| * might try to populate it. |
| * |
| * We atomically detach the top of branch from the tree, store the |
| * block number of its root in *@top, pointers to buffer_heads of |
| * partially truncated blocks - in @chain[].bh and pointers to |
| * their last elements that should not be removed - in |
| * @chain[].p. Return value is the pointer to last filled element |
| * of @chain. |
| * |
| * The work left to caller to do the actual freeing of subtrees: |
| * a) free the subtree starting from *@top |
| * b) free the subtrees whose roots are stored in |
| * (@chain[i].p+1 .. end of @chain[i].bh->b_data) |
| * c) free the subtrees growing from the inode past the @chain[0]. |
| * (no partially truncated stuff there). */ |
| |
| static Indirect *ext3_find_shared(struct inode *inode, |
| int depth, |
| int offsets[4], |
| Indirect chain[4], |
| u32 *top) |
| { |
| Indirect *partial, *p; |
| int k, err; |
| |
| *top = 0; |
| /* Make k index the deepest non-null offest + 1 */ |
| for (k = depth; k > 1 && !offsets[k-1]; k--) |
| ; |
| partial = ext3_get_branch(inode, k, offsets, chain, &err); |
| /* Writer: pointers */ |
| if (!partial) |
| partial = chain + k-1; |
| /* |
| * If the branch acquired continuation since we've looked at it - |
| * fine, it should all survive and (new) top doesn't belong to us. |
| */ |
| if (!partial->key && *partial->p) |
| /* Writer: end */ |
| goto no_top; |
| for (p=partial; p>chain && all_zeroes((u32*)p->bh->b_data,p->p); p--) |
| ; |
| /* |
| * OK, we've found the last block that must survive. The rest of our |
| * branch should be detached before unlocking. However, if that rest |
| * of branch is all ours and does not grow immediately from the inode |
| * it's easier to cheat and just decrement partial->p. |
| */ |
| if (p == chain + k - 1 && p > chain) { |
| p->p--; |
| } else { |
| *top = *p->p; |
| /* Nope, don't do this in ext3. Must leave the tree intact */ |
| #if 0 |
| *p->p = 0; |
| #endif |
| } |
| /* Writer: end */ |
| |
| while(partial > p) |
| { |
| brelse(partial->bh); |
| partial--; |
| } |
| no_top: |
| return partial; |
| } |
| |
| /* |
| * Zero a number of block pointers in either an inode or an indirect block. |
| * If we restart the transaction we must again get write access to the |
| * indirect block for further modification. |
| * |
| * We release `count' blocks on disk, but (last - first) may be greater |
| * than `count' because there can be holes in there. |
| */ |
| static void |
| ext3_clear_blocks(handle_t *handle, struct inode *inode, struct buffer_head *bh, |
| unsigned long block_to_free, unsigned long count, |
| u32 *first, u32 *last) |
| { |
| u32 *p; |
| if (try_to_extend_transaction(handle, inode)) { |
| if (bh) { |
| BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata"); |
| ext3_journal_dirty_metadata(handle, bh); |
| } |
| ext3_mark_inode_dirty(handle, inode); |
| ext3_journal_test_restart(handle, inode); |
| BUFFER_TRACE(bh, "get_write_access"); |
| ext3_journal_get_write_access(handle, bh); |
| } |
| |
| /* |
| * Any buffers which are on the journal will be in memory. We find |
| * them on the hash table so journal_revoke() will run journal_forget() |
| * on them. We've already detached each block from the file, so |
| * bforget() in journal_forget() should be safe. |
| * |
| * AKPM: turn on bforget in journal_forget()!!! |
| */ |
| for (p = first; p < last; p++) { |
| u32 nr = le32_to_cpu(*p); |
| if (nr) { |
| struct buffer_head *bh; |
| |
| *p = 0; |
| bh = sb_get_hash_table(inode->i_sb, nr); |
| ext3_forget(handle, 0, inode, bh, nr); |
| } |
| } |
| |
| ext3_free_blocks(handle, inode, block_to_free, count); |
| } |
| |
| /** |
| * ext3_free_data - free a list of data blocks |
| * @handle: handle for this transaction |
| * @inode: inode we are dealing with |
| * @this_bh: indirect buffer_head which contains *@first and *@last |
| * @first: array of block numbers |
| * @last: points immediately past the end of array |
| * |
| * We are freeing all blocks refered from that array (numbers are stored as |
| * little-endian 32-bit) and updating @inode->i_blocks appropriately. |
| * |
| * We accumulate contiguous runs of blocks to free. Conveniently, if these |
| * blocks are contiguous then releasing them at one time will only affect one |
| * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't |
| * actually use a lot of journal space. |
| * |
| * @this_bh will be %NULL if @first and @last point into the inode's direct |
| * block pointers. |
| */ |
| static void ext3_free_data(handle_t *handle, struct inode *inode, |
| struct buffer_head *this_bh, u32 *first, u32 *last) |
| { |
| unsigned long block_to_free = 0; /* Starting block # of a run */ |
| unsigned long count = 0; /* Number of blocks in the run */ |
| u32 *block_to_free_p = NULL; /* Pointer into inode/ind |
| corresponding to |
| block_to_free */ |
| unsigned long nr; /* Current block # */ |
| u32 *p; /* Pointer into inode/ind |
| for current block */ |
| int err; |
| |
| if (this_bh) { /* For indirect block */ |
| BUFFER_TRACE(this_bh, "get_write_access"); |
| err = ext3_journal_get_write_access(handle, this_bh); |
| /* Important: if we can't update the indirect pointers |
| * to the blocks, we can't free them. */ |
| if (err) |
| return; |
| } |
| |
| for (p = first; p < last; p++) { |
| nr = le32_to_cpu(*p); |
| if (nr) { |
| /* accumulate blocks to free if they're contiguous */ |
| if (count == 0) { |
| block_to_free = nr; |
| block_to_free_p = p; |
| count = 1; |
| } else if (nr == block_to_free + count) { |
| count++; |
| } else { |
| ext3_clear_blocks(handle, inode, this_bh, |
| block_to_free, |
| count, block_to_free_p, p); |
| block_to_free = nr; |
| block_to_free_p = p; |
| count = 1; |
| } |
| } |
| } |
| |
| if (count > 0) |
| ext3_clear_blocks(handle, inode, this_bh, block_to_free, |
| count, block_to_free_p, p); |
| |
| if (this_bh) { |
| BUFFER_TRACE(this_bh, "call ext3_journal_dirty_metadata"); |
| ext3_journal_dirty_metadata(handle, this_bh); |
| } |
| } |
| |
| /** |
| * ext3_free_branches - free an array of branches |
| * @handle: JBD handle for this transaction |
| * @inode: inode we are dealing with |
| * @parent_bh: the buffer_head which contains *@first and *@last |
| * @first: array of block numbers |
| * @last: pointer immediately past the end of array |
| * @depth: depth of the branches to free |
| * |
| * We are freeing all blocks refered from these branches (numbers are |
| * stored as little-endian 32-bit) and updating @inode->i_blocks |
| * appropriately. |
| */ |
| static void ext3_free_branches(handle_t *handle, struct inode *inode, |
| struct buffer_head *parent_bh, |
| u32 *first, u32 *last, int depth) |
| { |
| unsigned long nr; |
| u32 *p; |
| |
| if (is_handle_aborted(handle)) |
| return; |
| |
| if (depth--) { |
| struct buffer_head *bh; |
| int addr_per_block = EXT3_ADDR_PER_BLOCK(inode->i_sb); |
| p = last; |
| while (--p >= first) { |
| nr = le32_to_cpu(*p); |
| if (!nr) |
| continue; /* A hole */ |
| |
| /* Go read the buffer for the next level down */ |
| bh = sb_bread(inode->i_sb, nr); |
| |
| /* |
| * A read failure? Report error and clear slot |
| * (should be rare). |
| */ |
| if (!bh) { |
| ext3_error(inode->i_sb, "ext3_free_branches", |
| "Read failure, inode=%ld, block=%ld", |
| inode->i_ino, nr); |
| continue; |
| } |
| |
| /* This zaps the entire block. Bottom up. */ |
| BUFFER_TRACE(bh, "free child branches"); |
| ext3_free_branches(handle, inode, bh, (u32*)bh->b_data, |
| (u32*)bh->b_data + addr_per_block, |
| depth); |
| |
| /* |
| * We've probably journalled the indirect block several |
| * times during the truncate. But it's no longer |
| * needed and we now drop it from the transaction via |
| * journal_revoke(). |
| * |
| * That's easy if it's exclusively part of this |
| * transaction. But if it's part of the committing |
| * transaction then journal_forget() will simply |
| * brelse() it. That means that if the underlying |
| * block is reallocated in ext3_get_block(), |
| * unmap_underlying_metadata() will find this block |
| * and will try to get rid of it. damn, damn. |
| * |
| * If this block has already been committed to the |
| * journal, a revoke record will be written. And |
| * revoke records must be emitted *before* clearing |
| * this block's bit in the bitmaps. |
| */ |
| ext3_forget(handle, 1, inode, bh, bh->b_blocknr); |
| |
| /* |
| * Everything below this this pointer has been |
| * released. Now let this top-of-subtree go. |
| * |
| * We want the freeing of this indirect block to be |
| * atomic in the journal with the updating of the |
| * bitmap block which owns it. So make some room in |
| * the journal. |
| * |
| * We zero the parent pointer *after* freeing its |
| * pointee in the bitmaps, so if extend_transaction() |
| * for some reason fails to put the bitmap changes and |
| * the release into the same transaction, recovery |
| * will merely complain about releasing a free block, |
| * rather than leaking blocks. |
| */ |
| if (is_handle_aborted(handle)) |
| return; |
| if (try_to_extend_transaction(handle, inode)) { |
| ext3_mark_inode_dirty(handle, inode); |
| ext3_journal_test_restart(handle, inode); |
| } |
| |
| ext3_free_blocks(handle, inode, nr, 1); |
| |
| if (parent_bh) { |
| /* |
| * The block which we have just freed is |
| * pointed to by an indirect block: journal it |
| */ |
| BUFFER_TRACE(parent_bh, "get_write_access"); |
| if (!ext3_journal_get_write_access(handle, |
| parent_bh)){ |
| *p = 0; |
| BUFFER_TRACE(parent_bh, |
| "call ext3_journal_dirty_metadata"); |
| ext3_journal_dirty_metadata(handle, |
| parent_bh); |
| } |
| } |
| } |
| } else { |
| /* We have reached the bottom of the tree. */ |
| BUFFER_TRACE(parent_bh, "free data blocks"); |
| ext3_free_data(handle, inode, parent_bh, first, last); |
| } |
| } |
| |
| /* |
| * ext3_truncate() |
| * |
| * We block out ext3_get_block() block instantiations across the entire |
| * transaction, and VFS/VM ensures that ext3_truncate() cannot run |
| * simultaneously on behalf of the same inode. |
| * |
| * As we work through the truncate and commmit bits of it to the journal there |
| * is one core, guiding principle: the file's tree must always be consistent on |
| * disk. We must be able to restart the truncate after a crash. |
| * |
| * The file's tree may be transiently inconsistent in memory (although it |
| * probably isn't), but whenever we close off and commit a journal transaction, |
| * the contents of (the filesystem + the journal) must be consistent and |
| * restartable. It's pretty simple, really: bottom up, right to left (although |
| * left-to-right works OK too). |
| * |
| * Note that at recovery time, journal replay occurs *before* the restart of |
| * truncate against the orphan inode list. |
| * |
| * The committed inode has the new, desired i_size (which is the same as |
| * i_disksize in this case). After a crash, ext3_orphan_cleanup() will see |
| * that this inode's truncate did not complete and it will again call |
| * ext3_truncate() to have another go. So there will be instantiated blocks |
| * to the right of the truncation point in a crashed ext3 filesystem. But |
| * that's fine - as long as they are linked from the inode, the post-crash |
| * ext3_truncate() run will find them and release them. |
| */ |
| |
| void ext3_truncate(struct inode * inode) |
| { |
| handle_t *handle; |
| u32 *i_data = inode->u.ext3_i.i_data; |
| int addr_per_block = EXT3_ADDR_PER_BLOCK(inode->i_sb); |
| int offsets[4]; |
| Indirect chain[4]; |
| Indirect *partial; |
| int nr = 0; |
| int n; |
| long last_block; |
| unsigned blocksize; |
| |
| if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || |
| S_ISLNK(inode->i_mode))) |
| return; |
| if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) |
| return; |
| |
| ext3_discard_prealloc(inode); |
| |
| handle = start_transaction(inode); |
| if (IS_ERR(handle)) |
| return; /* AKPM: return what? */ |
| |
| blocksize = inode->i_sb->s_blocksize; |
| last_block = (inode->i_size + blocksize-1) |
| >> EXT3_BLOCK_SIZE_BITS(inode->i_sb); |
| |
| ext3_block_truncate_page(handle, inode->i_mapping, inode->i_size); |
| |
| |
| n = ext3_block_to_path(inode, last_block, offsets); |
| if (n == 0) |
| goto out_stop; /* error */ |
| |
| /* |
| * OK. This truncate is going to happen. We add the inode to the |
| * orphan list, so that if this truncate spans multiple transactions, |
| * and we crash, we will resume the truncate when the filesystem |
| * recovers. It also marks the inode dirty, to catch the new size. |
| * |
| * Implication: the file must always be in a sane, consistent |
| * truncatable state while each transaction commits. |
| */ |
| if (ext3_orphan_add(handle, inode)) |
| goto out_stop; |
| |
| /* |
| * The orphan list entry will now protect us from any crash which |
| * occurs before the truncate completes, so it is now safe to propagate |
| * the new, shorter inode size (held for now in i_size) into the |
| * on-disk inode. We do this via i_disksize, which is the value which |
| * ext3 *really* writes onto the disk inode. |
| */ |
| inode->u.ext3_i.i_disksize = inode->i_size; |
| |
| /* |
| * From here we block out all ext3_get_block() callers who want to |
| * modify the block allocation tree. |
| */ |
| down_write(&inode->u.ext3_i.truncate_sem); |
| |
| if (n == 1) { /* direct blocks */ |
| ext3_free_data(handle, inode, NULL, i_data+offsets[0], |
| i_data + EXT3_NDIR_BLOCKS); |
| goto do_indirects; |
| } |
| |
| partial = ext3_find_shared(inode, n, offsets, chain, &nr); |
| /* Kill the top of shared branch (not detached) */ |
| if (nr) { |
| if (partial == chain) { |
| /* Shared branch grows from the inode */ |
| ext3_free_branches(handle, inode, NULL, |
| &nr, &nr+1, (chain+n-1) - partial); |
| *partial->p = 0; |
| /* |
| * We mark the inode dirty prior to restart, |
| * and prior to stop. No need for it here. |
| */ |
| } else { |
| /* Shared branch grows from an indirect block */ |
| BUFFER_TRACE(partial->bh, "get_write_access"); |
| ext3_free_branches(handle, inode, partial->bh, |
| partial->p, |
| partial->p+1, (chain+n-1) - partial); |
| } |
| } |
| /* Clear the ends of indirect blocks on the shared branch */ |
| while (partial > chain) { |
| ext3_free_branches(handle, inode, partial->bh, partial->p + 1, |
| (u32*)partial->bh->b_data + addr_per_block, |
| (chain+n-1) - partial); |
| BUFFER_TRACE(partial->bh, "call brelse"); |
| brelse (partial->bh); |
| partial--; |
| } |
| do_indirects: |
| /* Kill the remaining (whole) subtrees */ |
| switch (offsets[0]) { |
| default: |
| nr = i_data[EXT3_IND_BLOCK]; |
| if (nr) { |
| ext3_free_branches(handle, inode, NULL, |
| &nr, &nr+1, 1); |
| i_data[EXT3_IND_BLOCK] = 0; |
| } |
| case EXT3_IND_BLOCK: |
| nr = i_data[EXT3_DIND_BLOCK]; |
| if (nr) { |
| ext3_free_branches(handle, inode, NULL, |
| &nr, &nr+1, 2); |
| i_data[EXT3_DIND_BLOCK] = 0; |
| } |
| case EXT3_DIND_BLOCK: |
| nr = i_data[EXT3_TIND_BLOCK]; |
| if (nr) { |
| ext3_free_branches(handle, inode, NULL, |
| &nr, &nr+1, 3); |
| i_data[EXT3_TIND_BLOCK] = 0; |
| } |
| case EXT3_TIND_BLOCK: |
| ; |
| } |
| up_write(&inode->u.ext3_i.truncate_sem); |
| inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
| ext3_mark_inode_dirty(handle, inode); |
| |
| /* In a multi-transaction truncate, we only make the final |
| * transaction synchronous */ |
| if (IS_SYNC(inode)) |
| handle->h_sync = 1; |
| out_stop: |
| /* |
| * If this was a simple ftruncate(), and the file will remain alive |
| * then we need to clear up the orphan record which we created above. |
| * However, if this was a real unlink then we were called by |
| * ext3_delete_inode(), and we allow that function to clean up the |
| * orphan info for us. |
| */ |
| if (inode->i_nlink) |
| ext3_orphan_del(handle, inode); |
| |
| ext3_journal_stop(handle, inode); |
| } |
| |
| /* |
| * ext3_get_inode_loc returns with an extra refcount against the |
| * inode's underlying buffer_head on success. |
| */ |
| |
| int ext3_get_inode_loc (struct inode *inode, struct ext3_iloc *iloc) |
| { |
| struct buffer_head *bh = 0; |
| unsigned long block; |
| unsigned long block_group; |
| unsigned long group_desc; |
| unsigned long desc; |
| unsigned long offset; |
| struct ext3_group_desc * gdp; |
| |
| if ((inode->i_ino != EXT3_ROOT_INO && |
| inode->i_ino != EXT3_ACL_IDX_INO && |
| inode->i_ino != EXT3_ACL_DATA_INO && |
| inode->i_ino != EXT3_JOURNAL_INO && |
| inode->i_ino < EXT3_FIRST_INO(inode->i_sb)) || |
| inode->i_ino > le32_to_cpu( |
| inode->i_sb->u.ext3_sb.s_es->s_inodes_count)) { |
| ext3_error (inode->i_sb, "ext3_get_inode_loc", |
| "bad inode number: %lu", inode->i_ino); |
| goto bad_inode; |
| } |
| block_group = (inode->i_ino - 1) / EXT3_INODES_PER_GROUP(inode->i_sb); |
| if (block_group >= inode->i_sb->u.ext3_sb.s_groups_count) { |
| ext3_error (inode->i_sb, "ext3_get_inode_loc", |
| "group >= groups count"); |
| goto bad_inode; |
| } |
| group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(inode->i_sb); |
| desc = block_group & (EXT3_DESC_PER_BLOCK(inode->i_sb) - 1); |
| bh = inode->i_sb->u.ext3_sb.s_group_desc[group_desc]; |
| if (!bh) { |
| ext3_error (inode->i_sb, "ext3_get_inode_loc", |
| "Descriptor not loaded"); |
| goto bad_inode; |
| } |
| |
| gdp = (struct ext3_group_desc *) bh->b_data; |
| /* |
| * Figure out the offset within the block group inode table |
| */ |
| offset = ((inode->i_ino - 1) % EXT3_INODES_PER_GROUP(inode->i_sb)) * |
| EXT3_INODE_SIZE(inode->i_sb); |
| block = le32_to_cpu(gdp[desc].bg_inode_table) + |
| (offset >> EXT3_BLOCK_SIZE_BITS(inode->i_sb)); |
| if (!(bh = sb_bread(inode->i_sb, block))) { |
| ext3_error (inode->i_sb, "ext3_get_inode_loc", |
| "unable to read inode block - " |
| "inode=%lu, block=%lu", inode->i_ino, block); |
| goto bad_inode; |
| } |
| offset &= (EXT3_BLOCK_SIZE(inode->i_sb) - 1); |
| |
| iloc->bh = bh; |
| iloc->raw_inode = (struct ext3_inode *) (bh->b_data + offset); |
| iloc->block_group = block_group; |
| |
| return 0; |
| |
| bad_inode: |
| return -EIO; |
| } |
| |
| void ext3_read_inode(struct inode * inode) |
| { |
| struct ext3_iloc iloc; |
| struct ext3_inode *raw_inode; |
| struct buffer_head *bh; |
| int block; |
| |
| if(ext3_get_inode_loc(inode, &iloc)) |
| goto bad_inode; |
| bh = iloc.bh; |
| raw_inode = iloc.raw_inode; |
| init_rwsem(&inode->u.ext3_i.truncate_sem); |
| inode->i_mode = le16_to_cpu(raw_inode->i_mode); |
| inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low); |
| inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low); |
| if(!(test_opt (inode->i_sb, NO_UID32))) { |
| inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16; |
| inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16; |
| } |
| inode->i_nlink = le16_to_cpu(raw_inode->i_links_count); |
| inode->i_size = le32_to_cpu(raw_inode->i_size); |
| inode->i_atime = le32_to_cpu(raw_inode->i_atime); |
| inode->i_ctime = le32_to_cpu(raw_inode->i_ctime); |
| inode->i_mtime = le32_to_cpu(raw_inode->i_mtime); |
| inode->u.ext3_i.i_dtime = le32_to_cpu(raw_inode->i_dtime); |
| /* We now have enough fields to check if the inode was active or not. |
| * This is needed because nfsd might try to access dead inodes |
| * the test is that same one that e2fsck uses |
| * NeilBrown 1999oct15 |
| */ |
| if (inode->i_nlink == 0) { |
| if (inode->i_mode == 0 || |
| !(inode->i_sb->u.ext3_sb.s_mount_state & EXT3_ORPHAN_FS)) { |
| /* this inode is deleted */ |
| brelse (bh); |
| goto bad_inode; |
| } |
| /* The only unlinked inodes we let through here have |
| * valid i_mode and are being read by the orphan |
| * recovery code: that's fine, we're about to complete |
| * the process of deleting those. */ |
| } |
| inode->i_blksize = PAGE_SIZE; /* This is the optimal IO size |
| * (for stat), not the fs block |
| * size */ |
| inode->i_blocks = le32_to_cpu(raw_inode->i_blocks); |
| inode->i_version = ++event; |
| inode->u.ext3_i.i_flags = le32_to_cpu(raw_inode->i_flags); |
| #ifdef EXT3_FRAGMENTS |
| inode->u.ext3_i.i_faddr = le32_to_cpu(raw_inode->i_faddr); |
| inode->u.ext3_i.i_frag_no = raw_inode->i_frag; |
| inode->u.ext3_i.i_frag_size = raw_inode->i_fsize; |
| #endif |
| inode->u.ext3_i.i_file_acl = le32_to_cpu(raw_inode->i_file_acl); |
| if (!S_ISREG(inode->i_mode)) { |
| inode->u.ext3_i.i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl); |
| } else { |
| inode->i_size |= |
| ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32; |
| } |
| inode->u.ext3_i.i_disksize = inode->i_size; |
| inode->i_generation = le32_to_cpu(raw_inode->i_generation); |
| #ifdef EXT3_PREALLOCATE |
| inode->u.ext3_i.i_prealloc_count = 0; |
| #endif |
| inode->u.ext3_i.i_block_group = iloc.block_group; |
| |
| /* |
| * NOTE! The in-memory inode i_data array is in little-endian order |
| * even on big-endian machines: we do NOT byteswap the block numbers! |
| */ |
| for (block = 0; block < EXT3_N_BLOCKS; block++) |
| inode->u.ext3_i.i_data[block] = iloc.raw_inode->i_block[block]; |
| INIT_LIST_HEAD(&inode->u.ext3_i.i_orphan); |
| |
| brelse (iloc.bh); |
| |
| if (inode->i_ino == EXT3_ACL_IDX_INO || |
| inode->i_ino == EXT3_ACL_DATA_INO) |
| /* Nothing to do */ ; |
| else if (S_ISREG(inode->i_mode)) { |
| inode->i_op = &ext3_file_inode_operations; |
| inode->i_fop = &ext3_file_operations; |
| inode->i_mapping->a_ops = &ext3_aops; |
| } else if (S_ISDIR(inode->i_mode)) { |
| inode->i_op = &ext3_dir_inode_operations; |
| inode->i_fop = &ext3_dir_operations; |
| } else if (S_ISLNK(inode->i_mode)) { |
| if (!inode->i_blocks) |
| inode->i_op = &ext3_fast_symlink_inode_operations; |
| else { |
| inode->i_op = &page_symlink_inode_operations; |
| inode->i_mapping->a_ops = &ext3_aops; |
| } |
| } else |
| init_special_inode(inode, inode->i_mode, |
| le32_to_cpu(iloc.raw_inode->i_block[0])); |
| /* inode->i_attr_flags = 0; unused */ |
| if (inode->u.ext3_i.i_flags & EXT3_SYNC_FL) { |
| /* inode->i_attr_flags |= ATTR_FLAG_SYNCRONOUS; unused */ |
| inode->i_flags |= S_SYNC; |
| } |
| if (inode->u.ext3_i.i_flags & EXT3_APPEND_FL) { |
| /* inode->i_attr_flags |= ATTR_FLAG_APPEND; unused */ |
| inode->i_flags |= S_APPEND; |
| } |
| if (inode->u.ext3_i.i_flags & EXT3_IMMUTABLE_FL) { |
| /* inode->i_attr_flags |= ATTR_FLAG_IMMUTABLE; unused */ |
| inode->i_flags |= S_IMMUTABLE; |
| } |
| if (inode->u.ext3_i.i_flags & EXT3_NOATIME_FL) { |
| /* inode->i_attr_flags |= ATTR_FLAG_NOATIME; unused */ |
| inode->i_flags |= S_NOATIME; |
| } |
| return; |
| |
| bad_inode: |
| make_bad_inode(inode); |
| return; |
| } |
| |
| /* |
| * Post the struct inode info into an on-disk inode location in the |
| * buffer-cache. This gobbles the caller's reference to the |
| * buffer_head in the inode location struct. |
| */ |
| |
| static int ext3_do_update_inode(handle_t *handle, |
| struct inode *inode, |
| struct ext3_iloc *iloc) |
| { |
| struct ext3_inode *raw_inode = iloc->raw_inode; |
| struct buffer_head *bh = iloc->bh; |
| int err = 0, rc, block; |
| |
| if (handle) { |
| BUFFER_TRACE(bh, "get_write_access"); |
| err = ext3_journal_get_write_access(handle, bh); |
| if (err) |
| goto out_brelse; |
| } |
| raw_inode->i_mode = cpu_to_le16(inode->i_mode); |
| if(!(test_opt(inode->i_sb, NO_UID32))) { |
| raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid)); |
| raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid)); |
| /* |
| * Fix up interoperability with old kernels. Otherwise, old inodes get |
| * re-used with the upper 16 bits of the uid/gid intact |
| */ |
| if(!inode->u.ext3_i.i_dtime) { |
| raw_inode->i_uid_high = |
| cpu_to_le16(high_16_bits(inode->i_uid)); |
| raw_inode->i_gid_high = |
| cpu_to_le16(high_16_bits(inode->i_gid)); |
| } else { |
| raw_inode->i_uid_high = 0; |
| raw_inode->i_gid_high = 0; |
| } |
| } else { |
| raw_inode->i_uid_low = |
| cpu_to_le16(fs_high2lowuid(inode->i_uid)); |
| raw_inode->i_gid_low = |
| cpu_to_le16(fs_high2lowgid(inode->i_gid)); |
| raw_inode->i_uid_high = 0; |
| raw_inode->i_gid_high = 0; |
| } |
| raw_inode->i_links_count = cpu_to_le16(inode->i_nlink); |
| raw_inode->i_size = cpu_to_le32(inode->u.ext3_i.i_disksize); |
| raw_inode->i_atime = cpu_to_le32(inode->i_atime); |
| raw_inode->i_ctime = cpu_to_le32(inode->i_ctime); |
| raw_inode->i_mtime = cpu_to_le32(inode->i_mtime); |
| raw_inode->i_blocks = cpu_to_le32(inode->i_blocks); |
| raw_inode->i_dtime = cpu_to_le32(inode->u.ext3_i.i_dtime); |
| raw_inode->i_flags = cpu_to_le32(inode->u.ext3_i.i_flags); |
| #ifdef EXT3_FRAGMENTS |
| raw_inode->i_faddr = cpu_to_le32(inode->u.ext3_i.i_faddr); |
| raw_inode->i_frag = inode->u.ext3_i.i_frag_no; |
| raw_inode->i_fsize = inode->u.ext3_i.i_frag_size; |
| #else |
| /* If we are not tracking these fields in the in-memory inode, |
| * then preserve them on disk, but still initialise them to zero |
| * for new inodes. */ |
| if (inode->u.ext3_i.i_state & EXT3_STATE_NEW) { |
| raw_inode->i_faddr = 0; |
| raw_inode->i_frag = 0; |
| raw_inode->i_fsize = 0; |
| } |
| #endif |
| raw_inode->i_file_acl = cpu_to_le32(inode->u.ext3_i.i_file_acl); |
| if (!S_ISREG(inode->i_mode)) { |
| raw_inode->i_dir_acl = cpu_to_le32(inode->u.ext3_i.i_dir_acl); |
| } else { |
| raw_inode->i_size_high = |
| cpu_to_le32(inode->u.ext3_i.i_disksize >> 32); |
| if (inode->u.ext3_i.i_disksize > 0x7fffffffULL) { |
| struct super_block *sb = inode->i_sb; |
| if (!EXT3_HAS_RO_COMPAT_FEATURE(sb, |
| EXT3_FEATURE_RO_COMPAT_LARGE_FILE) || |
| EXT3_SB(sb)->s_es->s_rev_level == |
| cpu_to_le32(EXT3_GOOD_OLD_REV)) { |
| /* If this is the first large file |
| * created, add a flag to the superblock. |
| */ |
| err = ext3_journal_get_write_access(handle, |
| sb->u.ext3_sb.s_sbh); |
| if (err) |
| goto out_brelse; |
| ext3_update_dynamic_rev(sb); |
| EXT3_SET_RO_COMPAT_FEATURE(sb, |
| EXT3_FEATURE_RO_COMPAT_LARGE_FILE); |
| sb->s_dirt = 1; |
| handle->h_sync = 1; |
| err = ext3_journal_dirty_metadata(handle, |
| sb->u.ext3_sb.s_sbh); |
| } |
| } |
| } |
| raw_inode->i_generation = le32_to_cpu(inode->i_generation); |
| if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) |
| raw_inode->i_block[0] = |
| cpu_to_le32(kdev_t_to_nr(inode->i_rdev)); |
| else for (block = 0; block < EXT3_N_BLOCKS; block++) |
| raw_inode->i_block[block] = inode->u.ext3_i.i_data[block]; |
| |
| BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata"); |
| rc = ext3_journal_dirty_metadata(handle, bh); |
| if (!err) |
| err = rc; |
| inode->u.ext3_i.i_state &= ~EXT3_STATE_NEW; |
| |
| out_brelse: |
| brelse (bh); |
| ext3_std_error(inode->i_sb, err); |
| return err; |
| } |
| |
| /* |
| * ext3_write_inode() |
| * |
| * We are called from a few places: |
| * |
| * - Within generic_file_write() for O_SYNC files. |
| * Here, there will be no transaction running. We wait for any running |
| * trasnaction to commit. |
| * |
| * - Within sys_sync(), kupdate and such. |
| * We wait on commit, if tol to. |
| * |
| * - Within prune_icache() (PF_MEMALLOC == true) |
| * Here we simply return. We can't afford to block kswapd on the |
| * journal commit. |
| * |
| * In all cases it is actually safe for us to return without doing anything, |
| * because the inode has been copied into a raw inode buffer in |
| * ext3_mark_inode_dirty(). This is a correctness thing for O_SYNC and for |
| * knfsd. |
| * |
| * Note that we are absolutely dependent upon all inode dirtiers doing the |
| * right thing: they *must* call mark_inode_dirty() after dirtying info in |
| * which we are interested. |
| * |
| * It would be a bug for them to not do this. The code: |
| * |
| * mark_inode_dirty(inode) |
| * stuff(); |
| * inode->i_size = expr; |
| * |
| * is in error because a kswapd-driven write_inode() could occur while |
| * `stuff()' is running, and the new i_size will be lost. Plus the inode |
| * will no longer be on the superblock's dirty inode list. |
| */ |
| void ext3_write_inode(struct inode *inode, int wait) |
| { |
| if (current->flags & PF_MEMALLOC) |
| return; |
| |
| if (ext3_journal_current_handle()) { |
| jbd_debug(0, "called recursively, non-PF_MEMALLOC!\n"); |
| return; |
| } |
| |
| if (!wait) |
| return; |
| |
| ext3_force_commit(inode->i_sb); |
| } |
| |
| /* |
| * ext3_setattr() |
| * |
| * Called from notify_change. |
| * |
| * We want to trap VFS attempts to truncate the file as soon as |
| * possible. In particular, we want to make sure that when the VFS |
| * shrinks i_size, we put the inode on the orphan list and modify |
| * i_disksize immediately, so that during the subsequent flushing of |
| * dirty pages and freeing of disk blocks, we can guarantee that any |
| * commit will leave the blocks being flushed in an unused state on |
| * disk. (On recovery, the inode will get truncated and the blocks will |
| * be freed, so we have a strong guarantee that no future commit will |
| * leave these blocks visible to the user.) |
| * |
| * This is only needed for regular files. rmdir() has its own path, and |
| * we can never truncate a direcory except on final unlink (at which |
| * point i_nlink is zero so recovery is easy.) |
| * |
| * Called with the BKL. |
| */ |
| |
| int ext3_setattr(struct dentry *dentry, struct iattr *attr) |
| { |
| struct inode *inode = dentry->d_inode; |
| int error, rc; |
| |
| error = inode_change_ok(inode, attr); |
| if (error) |
| return error; |
| |
| if (attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) { |
| handle_t *handle; |
| |
| handle = ext3_journal_start(inode, 3); |
| if (IS_ERR(handle)) { |
| error = PTR_ERR(handle); |
| goto err_out; |
| } |
| |
| error = ext3_orphan_add(handle, inode); |
| inode->u.ext3_i.i_disksize = attr->ia_size; |
| rc = ext3_mark_inode_dirty(handle, inode); |
| if (!error) |
| error = rc; |
| ext3_journal_stop(handle, inode); |
| } |
| |
| inode_setattr(inode, attr); |
| |
| /* If inode_setattr's call to ext3_truncate failed to get a |
| * transaction handle at all, we need to clean up the in-core |
| * orphan list manually. */ |
| if (inode->i_nlink) |
| ext3_orphan_del(NULL, inode); |
| |
| err_out: |
| ext3_std_error(inode->i_sb, error); |
| return 0; |
| } |
| |
| |
| /* |
| * akpm: how many blocks doth make a writepage()? |
| * |
| * With N blocks per page, it may be: |
| * N data blocks |
| * 2 indirect block |
| * 2 dindirect |
| * 1 tindirect |
| * N+5 bitmap blocks (from the above) |
| * N+5 group descriptor summary blocks |
| * 1 inode block |
| * 1 superblock. |
| * 2 * EXT3_SINGLEDATA_TRANS_BLOCKS for the quote files |
| * |
| * 3 * (N + 5) + 2 + 2 * EXT3_SINGLEDATA_TRANS_BLOCKS |
| * |
| * With ordered or writeback data it's the same, less the N data blocks. |
| * |
| * If the inode's direct blocks can hold an integral number of pages then a |
| * page cannot straddle two indirect blocks, and we can only touch one indirect |
| * and dindirect block, and the "5" above becomes "3". |
| * |
| * This still overestimates under most circumstances. If we were to pass the |
| * start and end offsets in here as well we could do block_to_path() on each |
| * block and work out the exact number of indirects which are touched. Pah. |
| */ |
| |
| int ext3_writepage_trans_blocks(struct inode *inode) |
| { |
| int bpp = ext3_journal_blocks_per_page(inode); |
| int indirects = (EXT3_NDIR_BLOCKS % bpp) ? 5 : 3; |
| int ret; |
| |
| if (ext3_should_journal_data(inode)) |
| ret = 3 * (bpp + indirects) + 2; |
| else |
| ret = 2 * (bpp + indirects) + 2; |
| |
| #ifdef CONFIG_QUOTA |
| ret += 2 * EXT3_SINGLEDATA_TRANS_BLOCKS; |
| #endif |
| |
| return ret; |
| } |
| |
| int |
| ext3_mark_iloc_dirty(handle_t *handle, |
| struct inode *inode, |
| struct ext3_iloc *iloc) |
| { |
| int err = 0; |
| |
| if (handle) { |
| /* the do_update_inode consumes one bh->b_count */ |
| atomic_inc(&iloc->bh->b_count); |
| err = ext3_do_update_inode(handle, inode, iloc); |
| /* ext3_do_update_inode() does journal_dirty_metadata */ |
| brelse(iloc->bh); |
| } else { |
| printk(KERN_EMERG __FUNCTION__ ": called with no handle!\n"); |
| } |
| return err; |
| } |
| |
| /* |
| * On success, We end up with an outstanding reference count against |
| * iloc->bh. This _must_ be cleaned up later. |
| */ |
| |
| int |
| ext3_reserve_inode_write(handle_t *handle, struct inode *inode, |
| struct ext3_iloc *iloc) |
| { |
| int err = 0; |
| if (handle) { |
| err = ext3_get_inode_loc(inode, iloc); |
| if (!err) { |
| BUFFER_TRACE(iloc->bh, "get_write_access"); |
| err = ext3_journal_get_write_access(handle, iloc->bh); |
| if (err) { |
| brelse(iloc->bh); |
| iloc->bh = NULL; |
| } |
| } |
| } |
| ext3_std_error(inode->i_sb, err); |
| return err; |
| } |
| |
| /* |
| * akpm: What we do here is to mark the in-core inode as clean |
| * with respect to inode dirtiness (it may still be data-dirty). |
| * This means that the in-core inode may be reaped by prune_icache |
| * without having to perform any I/O. This is a very good thing, |
| * because *any* task may call prune_icache - even ones which |
| * have a transaction open against a different journal. |
| * |
| * Is this cheating? Not really. Sure, we haven't written the |
| * inode out, but prune_icache isn't a user-visible syncing function. |
| * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync) |
| * we start and wait on commits. |
| * |
| * Is this efficient/effective? Well, we're being nice to the system |
| * by cleaning up our inodes proactively so they can be reaped |
| * without I/O. But we are potentially leaving up to five seconds' |
| * worth of inodes floating about which prune_icache wants us to |
| * write out. One way to fix that would be to get prune_icache() |
| * to do a write_super() to free up some memory. It has the desired |
| * effect. |
| */ |
| int ext3_mark_inode_dirty(handle_t *handle, struct inode *inode) |
| { |
| struct ext3_iloc iloc; |
| int err; |
| |
| err = ext3_reserve_inode_write(handle, inode, &iloc); |
| if (!err) |
| err = ext3_mark_iloc_dirty(handle, inode, &iloc); |
| return err; |
| } |
| |
| /* |
| * akpm: ext3_dirty_inode() is called from __mark_inode_dirty() |
| * |
| * We're really interested in the case where a file is being extended. |
| * i_size has been changed by generic_commit_write() and we thus need |
| * to include the updated inode in the current transaction. |
| * |
| * Also, DQUOT_ALLOC_SPACE() will always dirty the inode when blocks |
| * are allocated to the file. |
| * |
| * If the inode is marked synchronous, we don't honour that here - doing |
| * so would cause a commit on atime updates, which we don't bother doing. |
| * We handle synchronous inodes at the highest possible level. |
| */ |
| void ext3_dirty_inode(struct inode *inode) |
| { |
| handle_t *current_handle = ext3_journal_current_handle(); |
| handle_t *handle; |
| |
| lock_kernel(); |
| handle = ext3_journal_start(inode, 1); |
| if (IS_ERR(handle)) |
| goto out; |
| if (current_handle && |
| current_handle->h_transaction != handle->h_transaction) { |
| /* This task has a transaction open against a different fs */ |
| printk(KERN_EMERG __FUNCTION__": transactions do not match!\n"); |
| } else { |
| jbd_debug(5, "marking dirty. outer handle=%p\n", |
| current_handle); |
| ext3_mark_inode_dirty(handle, inode); |
| } |
| ext3_journal_stop(handle, inode); |
| out: |
| unlock_kernel(); |
| } |
| |
| #ifdef AKPM |
| /* |
| * Bind an inode's backing buffer_head into this transaction, to prevent |
| * it from being flushed to disk early. Unlike |
| * ext3_reserve_inode_write, this leaves behind no bh reference and |
| * returns no iloc structure, so the caller needs to repeat the iloc |
| * lookup to mark the inode dirty later. |
| */ |
| static inline int |
| ext3_pin_inode(handle_t *handle, struct inode *inode) |
| { |
| struct ext3_iloc iloc; |
| |
| int err = 0; |
| if (handle) { |
| err = ext3_get_inode_loc(inode, &iloc); |
| if (!err) { |
| BUFFER_TRACE(iloc.bh, "get_write_access"); |
| err = journal_get_write_access(handle, iloc.bh); |
| if (!err) |
| err = ext3_journal_dirty_metadata(handle, |
| iloc.bh); |
| brelse(iloc.bh); |
| } |
| } |
| ext3_std_error(inode->i_sb, err); |
| return err; |
| } |
| #endif |
| |
| int ext3_change_inode_journal_flag(struct inode *inode, int val) |
| { |
| journal_t *journal; |
| handle_t *handle; |
| int err; |
| |
| /* |
| * We have to be very careful here: changing a data block's |
| * journaling status dynamically is dangerous. If we write a |
| * data block to the journal, change the status and then delete |
| * that block, we risk forgetting to revoke the old log record |
| * from the journal and so a subsequent replay can corrupt data. |
| * So, first we make sure that the journal is empty and that |
| * nobody is changing anything. |
| */ |
| |
| journal = EXT3_JOURNAL(inode); |
| if (is_journal_aborted(journal) || IS_RDONLY(inode)) |
| return -EROFS; |
| |
| journal_lock_updates(journal); |
| journal_flush(journal); |
| |
| /* |
| * OK, there are no updates running now, and all cached data is |
| * synced to disk. We are now in a completely consistent state |
| * which doesn't have anything in the journal, and we know that |
| * no filesystem updates are running, so it is safe to modify |
| * the inode's in-core data-journaling state flag now. |
| */ |
| |
| if (val) |
| inode->u.ext3_i.i_flags |= EXT3_JOURNAL_DATA_FL; |
| else |
| inode->u.ext3_i.i_flags &= ~EXT3_JOURNAL_DATA_FL; |
| |
| journal_unlock_updates(journal); |
| |
| /* Finally we can mark the inode as dirty. */ |
| |
| handle = ext3_journal_start(inode, 1); |
| if (IS_ERR(handle)) |
| return PTR_ERR(handle); |
| |
| err = ext3_mark_inode_dirty(handle, inode); |
| handle->h_sync = 1; |
| ext3_journal_stop(handle, inode); |
| ext3_std_error(inode->i_sb, err); |
| |
| return err; |
| } |
| |
| |
| /* |
| * ext3_aops_journal_start(). |
| * |
| * <This function died, but the comment lives on> |
| * |
| * We need to take the inode semaphore *outside* the |
| * journal_start/journal_stop. Otherwise, a different task could do a |
| * wait_for_commit() while holding ->i_sem, which deadlocks. The rule |
| * is: transaction open/closes are considered to be a locking operation |
| * and they nest *inside* ->i_sem. |
| * ---------------------------------------------------------------------------- |
| * Possible problem: |
| * ext3_file_write() |
| * -> generic_file_write() |
| * -> __alloc_pages() |
| * -> page_launder() |
| * -> ext3_writepage() |
| * |
| * And the writepage can be on a different fs while we have a |
| * transaction open against this one! Bad. |
| * |
| * I tried making the task PF_MEMALLOC here, but that simply results in |
| * 0-order allocation failures passed back to generic_file_write(). |
| * Instead, we rely on the reentrancy protection in ext3_writepage(). |
| * ---------------------------------------------------------------------------- |
| * When we do the journal_start() here we don't really need to reserve |
| * any blocks - we won't need any until we hit ext3_prepare_write(), |
| * which does all the needed journal extending. However! There is a |
| * problem with quotas: |
| * |
| * Thread 1: |
| * sys_sync |
| * ->sync_dquots |
| * ->commit_dquot |
| * ->lock_dquot |
| * ->write_dquot |
| * ->ext3_file_write |
| * ->journal_start |
| * ->ext3_prepare_write |
| * ->journal_extend |
| * ->journal_start |
| * Thread 2: |
| * ext3_create (for example) |
| * ->ext3_new_inode |
| * ->dquot_initialize |
| * ->lock_dquot |
| * |
| * Deadlock. Thread 1's journal_start blocks because thread 2 has a |
| * transaction open. Thread 2's transaction will never close because |
| * thread 2 is stuck waiting for the dquot lock. |
| * |
| * So. We must ensure that thread 1 *never* needs to extend the journal |
| * for quota writes. We do that by reserving enough journal blocks |
| * here, in ext3_aops_journal_start() to ensure that the forthcoming "see if we |
| * need to extend" test in ext3_prepare_write() succeeds. |
| */ |
| |
| |
| MODULE_LICENSE("GPL"); |