| /* |
| * Resizable virtual memory filesystem for Linux. |
| * |
| * Copyright (C) 2000 Linus Torvalds. |
| * 2000 Transmeta Corp. |
| * 2000-2001 Christoph Rohland |
| * 2000-2001 SAP AG |
| * 2002 Red Hat Inc. |
| * Copyright (C) 2002-2003 Hugh Dickins. |
| * Copyright (C) 2002-2003 VERITAS Software Corporation. |
| * |
| * This file is released under the GPL. |
| */ |
| |
| /* |
| * This virtual memory filesystem is heavily based on the ramfs. It |
| * extends ramfs by the ability to use swap and honor resource limits |
| * which makes it a completely usable filesystem. |
| */ |
| |
| #include <linux/config.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/devfs_fs_kernel.h> |
| #include <linux/fs.h> |
| #include <linux/mm.h> |
| #include <linux/file.h> |
| #include <linux/swap.h> |
| #include <linux/pagemap.h> |
| #include <linux/string.h> |
| #include <linux/locks.h> |
| #include <linux/smp_lock.h> |
| |
| #include <asm/uaccess.h> |
| #include <asm/div64.h> |
| |
| /* This magic number is used in glibc for posix shared memory */ |
| #define TMPFS_MAGIC 0x01021994 |
| |
| #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) |
| #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) |
| #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) |
| |
| #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) |
| #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) |
| |
| #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) |
| |
| /* info->flags needs VM_flags to handle pagein/truncate race efficiently */ |
| #define SHMEM_PAGEIN VM_READ |
| #define SHMEM_TRUNCATE VM_WRITE |
| |
| /* Pretend that each entry is of this size in directory's i_size */ |
| #define BOGO_DIRENT_SIZE 20 |
| |
| #define SHMEM_SB(sb) (&sb->u.shmem_sb) |
| |
| /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ |
| enum sgp_type { |
| SGP_READ, /* don't exceed i_size, don't allocate page */ |
| SGP_CACHE, /* don't exceed i_size, may allocate page */ |
| SGP_WRITE, /* may exceed i_size, may allocate page */ |
| }; |
| |
| static int shmem_getpage(struct inode *inode, unsigned long idx, |
| struct page **pagep, enum sgp_type sgp); |
| |
| static struct super_operations shmem_ops; |
| static struct address_space_operations shmem_aops; |
| static struct file_operations shmem_file_operations; |
| static struct inode_operations shmem_inode_operations; |
| static struct inode_operations shmem_dir_inode_operations; |
| static struct vm_operations_struct shmem_vm_ops; |
| |
| LIST_HEAD(shmem_inodes); |
| static spinlock_t shmem_ilock = SPIN_LOCK_UNLOCKED; |
| |
| static void shmem_free_block(struct inode *inode) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| spin_lock(&sbinfo->stat_lock); |
| sbinfo->free_blocks++; |
| inode->i_blocks -= BLOCKS_PER_PAGE; |
| spin_unlock(&sbinfo->stat_lock); |
| } |
| |
| static void shmem_removepage(struct page *page) |
| { |
| if (!PageLaunder(page) && !PageError(page)) |
| shmem_free_block(page->mapping->host); |
| } |
| |
| /* |
| * shmem_swp_entry - find the swap vector position in the info structure |
| * |
| * @info: info structure for the inode |
| * @index: index of the page to find |
| * @page: optional page to add to the structure. Has to be preset to |
| * all zeros |
| * |
| * If there is no space allocated yet it will return NULL when |
| * page is 0, else it will use the page for the needed block, |
| * setting it to 0 on return to indicate that it has been used. |
| * |
| * The swap vector is organized the following way: |
| * |
| * There are SHMEM_NR_DIRECT entries directly stored in the |
| * shmem_inode_info structure. So small files do not need an addional |
| * allocation. |
| * |
| * For pages with index > SHMEM_NR_DIRECT there is the pointer |
| * i_indirect which points to a page which holds in the first half |
| * doubly indirect blocks, in the second half triple indirect blocks: |
| * |
| * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the |
| * following layout (for SHMEM_NR_DIRECT == 16): |
| * |
| * i_indirect -> dir --> 16-19 |
| * | +-> 20-23 |
| * | |
| * +-->dir2 --> 24-27 |
| * | +-> 28-31 |
| * | +-> 32-35 |
| * | +-> 36-39 |
| * | |
| * +-->dir3 --> 40-43 |
| * +-> 44-47 |
| * +-> 48-51 |
| * +-> 52-55 |
| */ |
| static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, unsigned long *page) |
| { |
| unsigned long offset; |
| void **dir; |
| |
| if (index < SHMEM_NR_DIRECT) |
| return info->i_direct+index; |
| if (!info->i_indirect) { |
| if (page) { |
| info->i_indirect = (void **) *page; |
| *page = 0; |
| } |
| return NULL; /* need another page */ |
| } |
| |
| index -= SHMEM_NR_DIRECT; |
| offset = index % ENTRIES_PER_PAGE; |
| index /= ENTRIES_PER_PAGE; |
| dir = info->i_indirect; |
| |
| if (index >= ENTRIES_PER_PAGE/2) { |
| index -= ENTRIES_PER_PAGE/2; |
| dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; |
| index %= ENTRIES_PER_PAGE; |
| if (!*dir) { |
| if (page) { |
| *dir = (void *) *page; |
| *page = 0; |
| } |
| return NULL; /* need another page */ |
| } |
| dir = (void **) *dir; |
| } |
| |
| dir += index; |
| if (!*dir) { |
| if (!page || !*page) |
| return NULL; /* need a page */ |
| *dir = (void *) *page; |
| *page = 0; |
| } |
| return (swp_entry_t *) *dir + offset; |
| } |
| |
| /* |
| * shmem_swp_alloc - get the position of the swap entry for the page. |
| * If it does not exist allocate the entry. |
| * |
| * @info: info structure for the inode |
| * @index: index of the page to find |
| * @sgp: check and recheck i_size? skip allocation? |
| */ |
| static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) |
| { |
| struct inode *inode = info->inode; |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| unsigned long page = 0; |
| swp_entry_t *entry; |
| static const swp_entry_t unswapped = {0}; |
| |
| if (sgp != SGP_WRITE && |
| ((loff_t) index << PAGE_CACHE_SHIFT) >= inode->i_size) |
| return ERR_PTR(-EINVAL); |
| |
| while (!(entry = shmem_swp_entry(info, index, &page))) { |
| if (sgp == SGP_READ) |
| return (swp_entry_t *) &unswapped; |
| /* |
| * Test free_blocks against 1 not 0, since we have 1 data |
| * page (and perhaps indirect index pages) yet to allocate: |
| * a waste to allocate index if we cannot allocate data. |
| */ |
| spin_lock(&sbinfo->stat_lock); |
| if (sbinfo->free_blocks <= 1) { |
| spin_unlock(&sbinfo->stat_lock); |
| return ERR_PTR(-ENOSPC); |
| } |
| sbinfo->free_blocks--; |
| inode->i_blocks += BLOCKS_PER_PAGE; |
| spin_unlock(&sbinfo->stat_lock); |
| |
| spin_unlock(&info->lock); |
| page = get_zeroed_page(GFP_USER); |
| spin_lock(&info->lock); |
| |
| if (!page) { |
| shmem_free_block(inode); |
| return ERR_PTR(-ENOMEM); |
| } |
| if (sgp != SGP_WRITE && |
| ((loff_t) index << PAGE_CACHE_SHIFT) >= inode->i_size) { |
| entry = ERR_PTR(-EINVAL); |
| break; |
| } |
| if (info->next_index <= index) |
| info->next_index = index + 1; |
| } |
| if (page) { |
| /* another task gave its page, or truncated the file */ |
| shmem_free_block(inode); |
| free_page(page); |
| } |
| if (info->next_index <= index && !IS_ERR(entry)) |
| info->next_index = index + 1; |
| return entry; |
| } |
| |
| /* |
| * shmem_free_swp - free some swap entries in a directory |
| * |
| * @dir: pointer to the directory |
| * @edir: pointer after last entry of the directory |
| */ |
| static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) |
| { |
| swp_entry_t *ptr; |
| int freed = 0; |
| |
| for (ptr = dir; ptr < edir; ptr++) { |
| if (ptr->val) { |
| free_swap_and_cache(*ptr); |
| *ptr = (swp_entry_t){0}; |
| freed++; |
| } |
| } |
| return freed; |
| } |
| |
| /* |
| * shmem_truncate_direct - free the swap entries of a whole doubly |
| * indirect block |
| * |
| * @info: the info structure of the inode |
| * @dir: pointer to the pointer to the block |
| * @start: offset to start from (in pages) |
| * @len: how many pages are stored in this block |
| */ |
| static inline unsigned long |
| shmem_truncate_direct(struct shmem_inode_info *info, swp_entry_t ***dir, unsigned long start, unsigned long len) |
| { |
| swp_entry_t **last, **ptr; |
| unsigned long off, freed_swp, freed = 0; |
| |
| last = *dir + (len + ENTRIES_PER_PAGE - 1) / ENTRIES_PER_PAGE; |
| off = start % ENTRIES_PER_PAGE; |
| |
| for (ptr = *dir + start/ENTRIES_PER_PAGE; ptr < last; ptr++, off = 0) { |
| if (!*ptr) |
| continue; |
| |
| if (info->swapped) { |
| freed_swp = shmem_free_swp(*ptr + off, |
| *ptr + ENTRIES_PER_PAGE); |
| info->swapped -= freed_swp; |
| freed += freed_swp; |
| } |
| |
| if (!off) { |
| freed++; |
| free_page((unsigned long) *ptr); |
| *ptr = 0; |
| } |
| } |
| |
| if (!start) { |
| freed++; |
| free_page((unsigned long) *dir); |
| *dir = 0; |
| } |
| return freed; |
| } |
| |
| /* |
| * shmem_truncate_indirect - truncate an inode |
| * |
| * @info: the info structure of the inode |
| * @index: the index to truncate |
| * |
| * This function locates the last doubly indirect block and calls |
| * then shmem_truncate_direct to do the real work |
| */ |
| static inline unsigned long |
| shmem_truncate_indirect(struct shmem_inode_info *info, unsigned long index) |
| { |
| swp_entry_t ***base; |
| unsigned long baseidx, start; |
| unsigned long len = info->next_index; |
| unsigned long freed; |
| |
| if (len <= SHMEM_NR_DIRECT) { |
| info->next_index = index; |
| if (!info->swapped) |
| return 0; |
| freed = shmem_free_swp(info->i_direct + index, |
| info->i_direct + len); |
| info->swapped -= freed; |
| return freed; |
| } |
| |
| if (len <= ENTRIES_PER_PAGEPAGE/2 + SHMEM_NR_DIRECT) { |
| len -= SHMEM_NR_DIRECT; |
| base = (swp_entry_t ***) &info->i_indirect; |
| baseidx = SHMEM_NR_DIRECT; |
| } else { |
| len -= ENTRIES_PER_PAGEPAGE/2 + SHMEM_NR_DIRECT; |
| BUG_ON(len > ENTRIES_PER_PAGEPAGE*ENTRIES_PER_PAGE/2); |
| baseidx = len - 1; |
| baseidx -= baseidx % ENTRIES_PER_PAGEPAGE; |
| base = (swp_entry_t ***) info->i_indirect + |
| ENTRIES_PER_PAGE/2 + baseidx/ENTRIES_PER_PAGEPAGE; |
| len -= baseidx; |
| baseidx += ENTRIES_PER_PAGEPAGE/2 + SHMEM_NR_DIRECT; |
| } |
| |
| if (index > baseidx) { |
| info->next_index = index; |
| start = index - baseidx; |
| } else { |
| info->next_index = baseidx; |
| start = 0; |
| } |
| return *base? shmem_truncate_direct(info, base, start, len): 0; |
| } |
| |
| static void shmem_truncate(struct inode *inode) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| unsigned long freed = 0; |
| unsigned long index; |
| |
| inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
| index = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| if (index >= info->next_index) |
| return; |
| |
| spin_lock(&info->lock); |
| while (index < info->next_index) |
| freed += shmem_truncate_indirect(info, index); |
| BUG_ON(info->swapped > info->next_index); |
| |
| if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { |
| /* |
| * Call truncate_inode_pages again: racing shmem_unuse_inode |
| * may have swizzled a page in from swap since vmtruncate or |
| * generic_delete_inode did it, before we lowered next_index. |
| * Also, though shmem_getpage checks i_size before adding to |
| * cache, no recheck after: so fix the narrow window there too. |
| */ |
| info->flags |= SHMEM_TRUNCATE; |
| spin_unlock(&info->lock); |
| truncate_inode_pages(inode->i_mapping, inode->i_size); |
| spin_lock(&info->lock); |
| info->flags &= ~SHMEM_TRUNCATE; |
| } |
| |
| spin_unlock(&info->lock); |
| spin_lock(&sbinfo->stat_lock); |
| sbinfo->free_blocks += freed; |
| inode->i_blocks -= freed*BLOCKS_PER_PAGE; |
| spin_unlock(&sbinfo->stat_lock); |
| } |
| |
| static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) |
| { |
| struct inode *inode = dentry->d_inode; |
| struct page *page = NULL; |
| int error; |
| |
| if (attr->ia_valid & ATTR_SIZE) { |
| if (attr->ia_size < inode->i_size) { |
| /* |
| * If truncating down to a partial page, then |
| * if that page is already allocated, hold it |
| * in memory until the truncation is over, so |
| * truncate_partial_page cannnot miss it were |
| * it assigned to swap. |
| */ |
| if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { |
| (void) shmem_getpage(inode, |
| attr->ia_size>>PAGE_CACHE_SHIFT, |
| &page, SGP_READ); |
| } |
| /* |
| * Reset SHMEM_PAGEIN flag so that shmem_truncate can |
| * detect if any pages might have been added to cache |
| * after truncate_inode_pages. But we needn't bother |
| * if it's being fully truncated to zero-length: the |
| * nrpages check is efficient enough in that case. |
| */ |
| if (attr->ia_size) { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| spin_lock(&info->lock); |
| info->flags &= ~SHMEM_PAGEIN; |
| spin_unlock(&info->lock); |
| } |
| } |
| } |
| |
| error = inode_change_ok(inode, attr); |
| if (!error) |
| error = inode_setattr(inode, attr); |
| if (page) |
| page_cache_release(page); |
| return error; |
| } |
| |
| static void shmem_delete_inode(struct inode *inode) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| |
| if (inode->i_op->truncate == shmem_truncate) { |
| spin_lock(&shmem_ilock); |
| list_del(&info->list); |
| spin_unlock(&shmem_ilock); |
| inode->i_size = 0; |
| shmem_truncate(inode); |
| } |
| BUG_ON(inode->i_blocks); |
| spin_lock(&sbinfo->stat_lock); |
| sbinfo->free_inodes++; |
| spin_unlock(&sbinfo->stat_lock); |
| clear_inode(inode); |
| } |
| |
| static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) |
| { |
| swp_entry_t *ptr; |
| |
| for (ptr = dir; ptr < edir; ptr++) { |
| if (ptr->val == entry.val) |
| return ptr - dir; |
| } |
| return -1; |
| } |
| |
| static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) |
| { |
| struct inode *inode; |
| struct address_space *mapping; |
| swp_entry_t *ptr; |
| unsigned long idx; |
| int offset; |
| |
| idx = 0; |
| ptr = info->i_direct; |
| spin_lock(&info->lock); |
| offset = info->next_index; |
| if (offset > SHMEM_NR_DIRECT) |
| offset = SHMEM_NR_DIRECT; |
| offset = shmem_find_swp(entry, ptr, ptr + offset); |
| if (offset >= 0) |
| goto found; |
| |
| for (idx = SHMEM_NR_DIRECT; idx < info->next_index; |
| idx += ENTRIES_PER_PAGE) { |
| ptr = shmem_swp_entry(info, idx, NULL); |
| if (!ptr) |
| continue; |
| offset = info->next_index - idx; |
| if (offset > ENTRIES_PER_PAGE) |
| offset = ENTRIES_PER_PAGE; |
| offset = shmem_find_swp(entry, ptr, ptr + offset); |
| if (offset >= 0) |
| goto found; |
| } |
| spin_unlock(&info->lock); |
| return 0; |
| found: |
| idx += offset; |
| inode = info->inode; |
| mapping = inode->i_mapping; |
| delete_from_swap_cache(page); |
| if (add_to_page_cache_unique(page, |
| mapping, idx, page_hash(mapping, idx)) == 0) { |
| info->flags |= SHMEM_PAGEIN; |
| ptr[offset].val = 0; |
| info->swapped--; |
| } else if (add_to_swap_cache(page, entry) != 0) |
| BUG(); |
| spin_unlock(&info->lock); |
| SetPageUptodate(page); |
| /* |
| * Decrement swap count even when the entry is left behind: |
| * try_to_unuse will skip over mms, then reincrement count. |
| */ |
| swap_free(entry); |
| return 1; |
| } |
| |
| /* |
| * shmem_unuse() search for an eventually swapped out shmem page. |
| */ |
| int shmem_unuse(swp_entry_t entry, struct page *page) |
| { |
| struct list_head *p; |
| struct shmem_inode_info *info; |
| int found = 0; |
| |
| spin_lock(&shmem_ilock); |
| list_for_each(p, &shmem_inodes) { |
| info = list_entry(p, struct shmem_inode_info, list); |
| |
| if (info->swapped && shmem_unuse_inode(info, entry, page)) { |
| /* move head to start search for next from here */ |
| list_move_tail(&shmem_inodes, &info->list); |
| found = 1; |
| break; |
| } |
| } |
| spin_unlock(&shmem_ilock); |
| return found; |
| } |
| |
| /* |
| * Move the page from the page cache to the swap cache. |
| */ |
| static int shmem_writepage(struct page *page) |
| { |
| struct shmem_inode_info *info; |
| swp_entry_t *entry, swap; |
| struct address_space *mapping; |
| unsigned long index; |
| struct inode *inode; |
| |
| BUG_ON(!PageLocked(page)); |
| if (!PageLaunder(page)) |
| goto fail; |
| |
| mapping = page->mapping; |
| index = page->index; |
| inode = mapping->host; |
| info = SHMEM_I(inode); |
| if (info->flags & VM_LOCKED) |
| goto fail; |
| getswap: |
| swap = get_swap_page(); |
| if (!swap.val) |
| goto fail; |
| |
| spin_lock(&info->lock); |
| if (index >= info->next_index) { |
| BUG_ON(!(info->flags & SHMEM_TRUNCATE)); |
| spin_unlock(&info->lock); |
| swap_free(swap); |
| goto fail; |
| } |
| entry = shmem_swp_entry(info, index, NULL); |
| BUG_ON(!entry); |
| BUG_ON(entry->val); |
| |
| /* Remove it from the page cache */ |
| remove_inode_page(page); |
| page_cache_release(page); |
| |
| /* Add it to the swap cache */ |
| if (add_to_swap_cache(page, swap) != 0) { |
| /* |
| * Raced with "speculative" read_swap_cache_async. |
| * Add page back to page cache, unref swap, try again. |
| */ |
| add_to_page_cache_locked(page, mapping, index); |
| info->flags |= SHMEM_PAGEIN; |
| spin_unlock(&info->lock); |
| swap_free(swap); |
| goto getswap; |
| } |
| |
| *entry = swap; |
| info->swapped++; |
| spin_unlock(&info->lock); |
| SetPageUptodate(page); |
| set_page_dirty(page); |
| UnlockPage(page); |
| return 0; |
| fail: |
| return fail_writepage(page); |
| } |
| |
| /* |
| * shmem_getpage - either get the page from swap or allocate a new one |
| * |
| * If we allocate a new one we do not mark it dirty. That's up to the |
| * vm. If we swap it in we mark it dirty since we also free the swap |
| * entry since a page cannot live in both the swap and page cache |
| */ |
| static int shmem_getpage(struct inode *inode, unsigned long idx, struct page **pagep, enum sgp_type sgp) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct shmem_sb_info *sbinfo; |
| struct page *filepage = *pagep; |
| struct page *swappage; |
| swp_entry_t *entry; |
| swp_entry_t swap; |
| int error = 0; |
| |
| if (idx >= SHMEM_MAX_INDEX) { |
| error = -EFBIG; |
| goto failed; |
| } |
| |
| /* |
| * Normally, filepage is NULL on entry, and either found |
| * uptodate immediately, or allocated and zeroed, or read |
| * in under swappage, which is then assigned to filepage. |
| * But shmem_readpage and shmem_prepare_write pass in a locked |
| * filepage, which may be found not uptodate by other callers |
| * too, and may need to be copied from the swappage read in. |
| */ |
| repeat: |
| if (!filepage) |
| filepage = find_lock_page(mapping, idx); |
| if (filepage && Page_Uptodate(filepage)) |
| goto done; |
| |
| spin_lock(&info->lock); |
| entry = shmem_swp_alloc(info, idx, sgp); |
| if (IS_ERR(entry)) { |
| spin_unlock(&info->lock); |
| error = PTR_ERR(entry); |
| goto failed; |
| } |
| swap = *entry; |
| |
| if (swap.val) { |
| /* Look it up and read it in.. */ |
| swappage = lookup_swap_cache(swap); |
| if (!swappage) { |
| spin_unlock(&info->lock); |
| swapin_readahead(swap); |
| swappage = read_swap_cache_async(swap); |
| if (!swappage) { |
| spin_lock(&info->lock); |
| entry = shmem_swp_alloc(info, idx, sgp); |
| if (IS_ERR(entry)) |
| error = PTR_ERR(entry); |
| else if (entry->val == swap.val) |
| error = -ENOMEM; |
| spin_unlock(&info->lock); |
| if (error) |
| goto failed; |
| goto repeat; |
| } |
| wait_on_page(swappage); |
| page_cache_release(swappage); |
| goto repeat; |
| } |
| |
| /* We have to do this with page locked to prevent races */ |
| if (TryLockPage(swappage)) { |
| spin_unlock(&info->lock); |
| wait_on_page(swappage); |
| page_cache_release(swappage); |
| goto repeat; |
| } |
| if (!Page_Uptodate(swappage)) { |
| spin_unlock(&info->lock); |
| UnlockPage(swappage); |
| page_cache_release(swappage); |
| error = -EIO; |
| goto failed; |
| } |
| |
| delete_from_swap_cache(swappage); |
| if (filepage) { |
| entry->val = 0; |
| info->swapped--; |
| spin_unlock(&info->lock); |
| flush_page_to_ram(swappage); |
| copy_highpage(filepage, swappage); |
| UnlockPage(swappage); |
| page_cache_release(swappage); |
| flush_dcache_page(filepage); |
| SetPageUptodate(filepage); |
| SetPageDirty(filepage); |
| swap_free(swap); |
| } else if (add_to_page_cache_unique(swappage, |
| mapping, idx, page_hash(mapping, idx)) == 0) { |
| info->flags |= SHMEM_PAGEIN; |
| entry->val = 0; |
| info->swapped--; |
| spin_unlock(&info->lock); |
| filepage = swappage; |
| SetPageUptodate(filepage); |
| SetPageDirty(filepage); |
| swap_free(swap); |
| } else { |
| if (add_to_swap_cache(swappage, swap) != 0) |
| BUG(); |
| spin_unlock(&info->lock); |
| SetPageUptodate(swappage); |
| SetPageDirty(swappage); |
| UnlockPage(swappage); |
| page_cache_release(swappage); |
| goto repeat; |
| } |
| } else if (sgp == SGP_READ && !filepage) { |
| filepage = find_get_page(mapping, idx); |
| if (filepage && |
| (!Page_Uptodate(filepage) || TryLockPage(filepage))) { |
| spin_unlock(&info->lock); |
| wait_on_page(filepage); |
| page_cache_release(filepage); |
| filepage = NULL; |
| goto repeat; |
| } |
| spin_unlock(&info->lock); |
| } else { |
| sbinfo = SHMEM_SB(inode->i_sb); |
| spin_lock(&sbinfo->stat_lock); |
| if (sbinfo->free_blocks == 0) { |
| spin_unlock(&sbinfo->stat_lock); |
| spin_unlock(&info->lock); |
| error = -ENOSPC; |
| goto failed; |
| } |
| sbinfo->free_blocks--; |
| inode->i_blocks += BLOCKS_PER_PAGE; |
| spin_unlock(&sbinfo->stat_lock); |
| |
| if (!filepage) { |
| spin_unlock(&info->lock); |
| filepage = page_cache_alloc(mapping); |
| if (!filepage) { |
| shmem_free_block(inode); |
| error = -ENOMEM; |
| goto failed; |
| } |
| |
| spin_lock(&info->lock); |
| entry = shmem_swp_alloc(info, idx, sgp); |
| if (IS_ERR(entry)) |
| error = PTR_ERR(entry); |
| if (error || entry->val || |
| add_to_page_cache_unique(filepage, |
| mapping, idx, page_hash(mapping, idx)) != 0) { |
| spin_unlock(&info->lock); |
| page_cache_release(filepage); |
| shmem_free_block(inode); |
| filepage = NULL; |
| if (error) |
| goto failed; |
| goto repeat; |
| } |
| info->flags |= SHMEM_PAGEIN; |
| } |
| |
| spin_unlock(&info->lock); |
| clear_highpage(filepage); |
| flush_dcache_page(filepage); |
| SetPageUptodate(filepage); |
| } |
| done: |
| if (!*pagep) { |
| if (filepage) |
| UnlockPage(filepage); |
| else |
| filepage = ZERO_PAGE(0); |
| *pagep = filepage; |
| } |
| if (PageError(filepage)) |
| ClearPageError(filepage); |
| return 0; |
| |
| failed: |
| if (filepage) { |
| if (*pagep == filepage) |
| SetPageError(filepage); |
| else { |
| UnlockPage(filepage); |
| page_cache_release(filepage); |
| } |
| } |
| return error; |
| } |
| |
| struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int unused) |
| { |
| struct inode *inode = vma->vm_file->f_dentry->d_inode; |
| struct page *page = NULL; |
| unsigned long idx; |
| int error; |
| |
| idx = (address - vma->vm_start) >> PAGE_SHIFT; |
| idx += vma->vm_pgoff; |
| idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; |
| |
| error = shmem_getpage(inode, idx, &page, SGP_CACHE); |
| if (error) |
| return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; |
| |
| mark_page_accessed(page); |
| flush_page_to_ram(page); |
| return page; |
| } |
| |
| void shmem_lock(struct file *file, int lock) |
| { |
| struct inode *inode = file->f_dentry->d_inode; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| |
| spin_lock(&info->lock); |
| if (lock) |
| info->flags |= VM_LOCKED; |
| else |
| info->flags &= ~VM_LOCKED; |
| spin_unlock(&info->lock); |
| } |
| |
| static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
| { |
| struct vm_operations_struct *ops; |
| struct inode *inode = file->f_dentry->d_inode; |
| |
| ops = &shmem_vm_ops; |
| if (!S_ISREG(inode->i_mode)) |
| return -EACCES; |
| UPDATE_ATIME(inode); |
| vma->vm_ops = ops; |
| return 0; |
| } |
| |
| static struct inode *shmem_get_inode(struct super_block *sb, int mode, int dev) |
| { |
| struct inode *inode; |
| struct shmem_inode_info *info; |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| |
| spin_lock(&sbinfo->stat_lock); |
| if (!sbinfo->free_inodes) { |
| spin_unlock(&sbinfo->stat_lock); |
| return NULL; |
| } |
| sbinfo->free_inodes--; |
| spin_unlock(&sbinfo->stat_lock); |
| |
| inode = new_inode(sb); |
| if (inode) { |
| inode->i_mode = mode; |
| inode->i_uid = current->fsuid; |
| inode->i_gid = current->fsgid; |
| inode->i_blksize = PAGE_CACHE_SIZE; |
| inode->i_blocks = 0; |
| inode->i_rdev = NODEV; |
| inode->i_mapping->a_ops = &shmem_aops; |
| inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
| info = SHMEM_I(inode); |
| info->inode = inode; |
| spin_lock_init(&info->lock); |
| switch (mode & S_IFMT) { |
| default: |
| init_special_inode(inode, mode, dev); |
| break; |
| case S_IFREG: |
| inode->i_op = &shmem_inode_operations; |
| inode->i_fop = &shmem_file_operations; |
| spin_lock(&shmem_ilock); |
| list_add_tail(&info->list, &shmem_inodes); |
| spin_unlock(&shmem_ilock); |
| break; |
| case S_IFDIR: |
| inode->i_nlink++; |
| /* Some things misbehave if size == 0 on a directory */ |
| inode->i_size = 2 * BOGO_DIRENT_SIZE; |
| inode->i_op = &shmem_dir_inode_operations; |
| inode->i_fop = &dcache_dir_ops; |
| break; |
| case S_IFLNK: |
| break; |
| } |
| } |
| return inode; |
| } |
| |
| static int shmem_set_size(struct shmem_sb_info *info, |
| unsigned long max_blocks, unsigned long max_inodes) |
| { |
| int error; |
| unsigned long blocks, inodes; |
| |
| spin_lock(&info->stat_lock); |
| blocks = info->max_blocks - info->free_blocks; |
| inodes = info->max_inodes - info->free_inodes; |
| error = -EINVAL; |
| if (max_blocks < blocks) |
| goto out; |
| if (max_inodes < inodes) |
| goto out; |
| error = 0; |
| info->max_blocks = max_blocks; |
| info->free_blocks = max_blocks - blocks; |
| info->max_inodes = max_inodes; |
| info->free_inodes = max_inodes - inodes; |
| out: |
| spin_unlock(&info->stat_lock); |
| return error; |
| } |
| |
| #ifdef CONFIG_TMPFS |
| |
| static struct inode_operations shmem_symlink_inode_operations; |
| static struct inode_operations shmem_symlink_inline_operations; |
| |
| /* |
| * tmpfs itself makes no use of generic_file_read, generic_file_mmap |
| * or generic_file_write; but shmem_readpage, shmem_prepare_write and |
| * shmem_commit_write let a tmpfs file be used below the loop driver, |
| * and shmem_readpage lets a tmpfs file be used by sendfile. |
| */ |
| static int |
| shmem_readpage(struct file *file, struct page *page) |
| { |
| struct inode *inode = page->mapping->host; |
| int error = shmem_getpage(inode, page->index, &page, SGP_CACHE); |
| UnlockPage(page); |
| return error; |
| } |
| |
| static int |
| shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) |
| { |
| struct inode *inode = page->mapping->host; |
| return shmem_getpage(inode, page->index, &page, SGP_WRITE); |
| } |
| |
| static int |
| shmem_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to) |
| { |
| struct inode *inode = page->mapping->host; |
| loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; |
| |
| if (pos > inode->i_size) |
| inode->i_size = pos; |
| SetPageDirty(page); |
| return 0; |
| } |
| |
| static ssize_t |
| shmem_file_write(struct file *file, const char *buf, size_t count, loff_t *ppos) |
| { |
| struct inode *inode = file->f_dentry->d_inode; |
| loff_t pos; |
| unsigned long written; |
| ssize_t err; |
| |
| if ((ssize_t) count < 0) |
| return -EINVAL; |
| |
| if (!access_ok(VERIFY_READ, buf, count)) |
| return -EFAULT; |
| |
| down(&inode->i_sem); |
| |
| pos = *ppos; |
| written = 0; |
| |
| err = precheck_file_write(file, inode, &count, &pos); |
| if (err || !count) |
| goto out; |
| |
| remove_suid(inode); |
| inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
| |
| do { |
| struct page *page = NULL; |
| unsigned long bytes, index, offset; |
| char *kaddr; |
| int left; |
| |
| offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ |
| index = pos >> PAGE_CACHE_SHIFT; |
| bytes = PAGE_CACHE_SIZE - offset; |
| if (bytes > count) |
| bytes = count; |
| |
| /* |
| * We don't hold page lock across copy from user - |
| * what would it guard against? - so no deadlock here. |
| */ |
| |
| err = shmem_getpage(inode, index, &page, SGP_WRITE); |
| if (err) |
| break; |
| |
| kaddr = kmap(page); |
| left = __copy_from_user(kaddr + offset, buf, bytes); |
| kunmap(page); |
| |
| written += bytes; |
| count -= bytes; |
| pos += bytes; |
| buf += bytes; |
| if (pos > inode->i_size) |
| inode->i_size = pos; |
| |
| flush_dcache_page(page); |
| SetPageDirty(page); |
| SetPageReferenced(page); |
| page_cache_release(page); |
| |
| if (left) { |
| pos -= left; |
| written -= left; |
| err = -EFAULT; |
| break; |
| } |
| } while (count); |
| |
| *ppos = pos; |
| if (written) |
| err = written; |
| out: |
| up(&inode->i_sem); |
| return err; |
| } |
| |
| static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc) |
| { |
| struct inode *inode = filp->f_dentry->d_inode; |
| struct address_space *mapping = inode->i_mapping; |
| unsigned long index, offset; |
| loff_t pos = *ppos; |
| |
| if (unlikely(pos < 0)) |
| return; |
| |
| index = pos >> PAGE_CACHE_SHIFT; |
| offset = pos & ~PAGE_CACHE_MASK; |
| |
| for (;;) { |
| struct page *page = NULL; |
| unsigned long end_index, nr, ret; |
| |
| end_index = inode->i_size >> PAGE_CACHE_SHIFT; |
| if (index > end_index) |
| break; |
| if (index == end_index) { |
| nr = inode->i_size & ~PAGE_CACHE_MASK; |
| if (nr <= offset) |
| break; |
| } |
| |
| desc->error = shmem_getpage(inode, index, &page, SGP_READ); |
| if (desc->error) { |
| if (desc->error == -EINVAL) |
| desc->error = 0; |
| break; |
| } |
| |
| /* |
| * We must evaluate after, since reads (unlike writes) |
| * are called without i_sem protection against truncate |
| */ |
| nr = PAGE_CACHE_SIZE; |
| end_index = inode->i_size >> PAGE_CACHE_SHIFT; |
| if (index == end_index) { |
| nr = inode->i_size & ~PAGE_CACHE_MASK; |
| if (nr <= offset) { |
| page_cache_release(page); |
| break; |
| } |
| } |
| nr -= offset; |
| |
| if (page != ZERO_PAGE(0)) { |
| /* |
| * If users can be writing to this page using arbitrary |
| * virtual addresses, take care about potential aliasing |
| * before reading the page on the kernel side. |
| */ |
| if (mapping->i_mmap_shared != NULL) |
| flush_dcache_page(page); |
| /* |
| * Mark the page accessed if we read the |
| * beginning or we just did an lseek. |
| */ |
| if (!offset || !filp->f_reada) |
| mark_page_accessed(page); |
| } |
| |
| /* |
| * Ok, we have the page, and it's up-to-date, so |
| * now we can copy it to user space... |
| * |
| * The actor routine returns how many bytes were actually used.. |
| * NOTE! This may not be the same as how much of a user buffer |
| * we filled up (we may be padding etc), so we can only update |
| * "pos" here (the actor routine has to update the user buffer |
| * pointers and the remaining count). |
| */ |
| ret = file_read_actor(desc, page, offset, nr); |
| offset += ret; |
| index += offset >> PAGE_CACHE_SHIFT; |
| offset &= ~PAGE_CACHE_MASK; |
| |
| page_cache_release(page); |
| if (ret != nr || !desc->count) |
| break; |
| } |
| |
| *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
| filp->f_reada = 1; |
| UPDATE_ATIME(inode); |
| } |
| |
| static ssize_t shmem_file_read(struct file *filp, char *buf, size_t count, loff_t *ppos) |
| { |
| read_descriptor_t desc; |
| |
| if ((ssize_t) count < 0) |
| return -EINVAL; |
| if (!access_ok(VERIFY_WRITE, buf, count)) |
| return -EFAULT; |
| if (!count) |
| return 0; |
| |
| desc.written = 0; |
| desc.count = count; |
| desc.buf = buf; |
| desc.error = 0; |
| |
| do_shmem_file_read(filp, ppos, &desc); |
| if (desc.written) |
| return desc.written; |
| return desc.error; |
| } |
| |
| static int shmem_statfs(struct super_block *sb, struct statfs *buf) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| |
| buf->f_type = TMPFS_MAGIC; |
| buf->f_bsize = PAGE_CACHE_SIZE; |
| spin_lock(&sbinfo->stat_lock); |
| buf->f_blocks = sbinfo->max_blocks; |
| buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; |
| buf->f_files = sbinfo->max_inodes; |
| buf->f_ffree = sbinfo->free_inodes; |
| spin_unlock(&sbinfo->stat_lock); |
| buf->f_namelen = NAME_MAX; |
| return 0; |
| } |
| |
| /* |
| * Retaining negative dentries for an in-memory filesystem just wastes |
| * memory and lookup time: arrange for them to be deleted immediately. |
| */ |
| static int shmem_delete_dentry(struct dentry *dentry) |
| { |
| return 1; |
| } |
| |
| /* |
| * Lookup the data. This is trivial - if the dentry didn't already |
| * exist, we know it is negative. Set d_op to delete negative dentries. |
| */ |
| static struct dentry *shmem_lookup(struct inode *dir, struct dentry *dentry) |
| { |
| static struct dentry_operations shmem_dentry_operations = { |
| .d_delete = shmem_delete_dentry, |
| }; |
| |
| if (dentry->d_name.len > NAME_MAX) |
| return ERR_PTR(-ENAMETOOLONG); |
| dentry->d_op = &shmem_dentry_operations; |
| d_add(dentry, NULL); |
| return NULL; |
| } |
| |
| /* |
| * File creation. Allocate an inode, and we're done.. |
| */ |
| static int shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, int dev) |
| { |
| struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); |
| int error = -ENOSPC; |
| |
| if (inode) { |
| if (dir->i_mode & S_ISGID) { |
| inode->i_gid = dir->i_gid; |
| if (S_ISDIR(mode)) |
| inode->i_mode |= S_ISGID; |
| } |
| dir->i_size += BOGO_DIRENT_SIZE; |
| dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| d_instantiate(dentry, inode); |
| dget(dentry); /* Extra count - pin the dentry in core */ |
| error = 0; |
| } |
| return error; |
| } |
| |
| static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
| { |
| int error; |
| |
| if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) |
| return error; |
| dir->i_nlink++; |
| return 0; |
| } |
| |
| static int shmem_create(struct inode *dir, struct dentry *dentry, int mode) |
| { |
| return shmem_mknod(dir, dentry, mode | S_IFREG, 0); |
| } |
| |
| /* |
| * Link a file.. |
| */ |
| static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
| { |
| struct inode *inode = old_dentry->d_inode; |
| |
| if (S_ISDIR(inode->i_mode)) |
| return -EPERM; |
| |
| dir->i_size += BOGO_DIRENT_SIZE; |
| inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| inode->i_nlink++; |
| atomic_inc(&inode->i_count); /* New dentry reference */ |
| dget(dentry); /* Extra pinning count for the created dentry */ |
| d_instantiate(dentry, inode); |
| return 0; |
| } |
| |
| static inline int shmem_positive(struct dentry *dentry) |
| { |
| return dentry->d_inode && !d_unhashed(dentry); |
| } |
| |
| /* |
| * Check that a directory is empty (this works |
| * for regular files too, they'll just always be |
| * considered empty..). |
| * |
| * Note that an empty directory can still have |
| * children, they just all have to be negative.. |
| */ |
| static int shmem_empty(struct dentry *dentry) |
| { |
| struct list_head *list; |
| |
| spin_lock(&dcache_lock); |
| list = dentry->d_subdirs.next; |
| |
| while (list != &dentry->d_subdirs) { |
| struct dentry *de = list_entry(list, struct dentry, d_child); |
| |
| if (shmem_positive(de)) { |
| spin_unlock(&dcache_lock); |
| return 0; |
| } |
| list = list->next; |
| } |
| spin_unlock(&dcache_lock); |
| return 1; |
| } |
| |
| static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
| { |
| struct inode *inode = dentry->d_inode; |
| |
| dir->i_size -= BOGO_DIRENT_SIZE; |
| inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| inode->i_nlink--; |
| dput(dentry); /* Undo the count from "create" - this does all the work */ |
| return 0; |
| } |
| |
| static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
| { |
| if (!shmem_empty(dentry)) |
| return -ENOTEMPTY; |
| |
| dir->i_nlink--; |
| return shmem_unlink(dir, dentry); |
| } |
| |
| /* |
| * The VFS layer already does all the dentry stuff for rename, |
| * we just have to decrement the usage count for the target if |
| * it exists so that the VFS layer correctly free's it when it |
| * gets overwritten. |
| */ |
| static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
| { |
| struct inode *inode = old_dentry->d_inode; |
| int they_are_dirs = S_ISDIR(inode->i_mode); |
| |
| if (!shmem_empty(new_dentry)) |
| return -ENOTEMPTY; |
| |
| if (new_dentry->d_inode) { |
| (void) shmem_unlink(new_dir, new_dentry); |
| if (they_are_dirs) |
| old_dir->i_nlink--; |
| } else if (they_are_dirs) { |
| old_dir->i_nlink--; |
| new_dir->i_nlink++; |
| } |
| |
| old_dir->i_size -= BOGO_DIRENT_SIZE; |
| new_dir->i_size += BOGO_DIRENT_SIZE; |
| old_dir->i_ctime = old_dir->i_mtime = |
| new_dir->i_ctime = new_dir->i_mtime = |
| inode->i_ctime = CURRENT_TIME; |
| return 0; |
| } |
| |
| static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
| { |
| int error; |
| int len; |
| struct inode *inode; |
| struct page *page = NULL; |
| char *kaddr; |
| struct shmem_inode_info *info; |
| |
| len = strlen(symname) + 1; |
| if (len > PAGE_CACHE_SIZE) |
| return -ENAMETOOLONG; |
| |
| inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); |
| if (!inode) |
| return -ENOSPC; |
| |
| info = SHMEM_I(inode); |
| inode->i_size = len-1; |
| if (len <= sizeof(struct shmem_inode_info)) { |
| /* do it inline */ |
| memcpy(info, symname, len); |
| inode->i_op = &shmem_symlink_inline_operations; |
| } else { |
| error = shmem_getpage(inode, 0, &page, SGP_WRITE); |
| if (error) { |
| iput(inode); |
| return error; |
| } |
| inode->i_op = &shmem_symlink_inode_operations; |
| spin_lock(&shmem_ilock); |
| list_add_tail(&info->list, &shmem_inodes); |
| spin_unlock(&shmem_ilock); |
| kaddr = kmap(page); |
| memcpy(kaddr, symname, len); |
| kunmap(page); |
| SetPageDirty(page); |
| page_cache_release(page); |
| } |
| if (dir->i_mode & S_ISGID) |
| inode->i_gid = dir->i_gid; |
| dir->i_size += BOGO_DIRENT_SIZE; |
| dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| d_instantiate(dentry, inode); |
| dget(dentry); |
| return 0; |
| } |
| |
| static int shmem_readlink_inline(struct dentry *dentry, char *buffer, int buflen) |
| { |
| return vfs_readlink(dentry, buffer, buflen, (const char *)SHMEM_I(dentry->d_inode)); |
| } |
| |
| static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) |
| { |
| return vfs_follow_link(nd, (const char *)SHMEM_I(dentry->d_inode)); |
| } |
| |
| static int shmem_readlink(struct dentry *dentry, char *buffer, int buflen) |
| { |
| struct page *page = NULL; |
| int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ); |
| if (res) |
| return res; |
| res = vfs_readlink(dentry, buffer, buflen, kmap(page)); |
| kunmap(page); |
| mark_page_accessed(page); |
| page_cache_release(page); |
| return res; |
| } |
| |
| static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd) |
| { |
| struct page *page = NULL; |
| int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ); |
| if (res) |
| return res; |
| res = vfs_follow_link(nd, kmap(page)); |
| kunmap(page); |
| mark_page_accessed(page); |
| page_cache_release(page); |
| return res; |
| } |
| |
| static struct inode_operations shmem_symlink_inline_operations = { |
| readlink: shmem_readlink_inline, |
| follow_link: shmem_follow_link_inline, |
| }; |
| |
| static struct inode_operations shmem_symlink_inode_operations = { |
| truncate: shmem_truncate, |
| readlink: shmem_readlink, |
| follow_link: shmem_follow_link, |
| }; |
| |
| static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes) |
| { |
| char *this_char, *value, *rest; |
| |
| while ((this_char = strsep(&options, ",")) != NULL) { |
| if (!*this_char) |
| continue; |
| if ((value = strchr(this_char,'=')) != NULL) { |
| *value++ = 0; |
| } else { |
| printk(KERN_ERR |
| "tmpfs: No value for mount option '%s'\n", |
| this_char); |
| return 1; |
| } |
| |
| if (!strcmp(this_char,"size")) { |
| unsigned long long size; |
| size = memparse(value,&rest); |
| if (*rest == '%') { |
| struct sysinfo si; |
| si_meminfo(&si); |
| size <<= PAGE_SHIFT; |
| size *= si.totalram; |
| do_div(size, 100); |
| rest++; |
| } |
| if (*rest) |
| goto bad_val; |
| *blocks = size >> PAGE_CACHE_SHIFT; |
| } else if (!strcmp(this_char,"nr_blocks")) { |
| *blocks = memparse(value,&rest); |
| if (*rest) |
| goto bad_val; |
| } else if (!strcmp(this_char,"nr_inodes")) { |
| *inodes = memparse(value,&rest); |
| if (*rest) |
| goto bad_val; |
| } else if (!strcmp(this_char,"mode")) { |
| if (!mode) |
| continue; |
| *mode = simple_strtoul(value,&rest,8); |
| if (*rest) |
| goto bad_val; |
| } else if (!strcmp(this_char,"uid")) { |
| if (!uid) |
| continue; |
| *uid = simple_strtoul(value,&rest,0); |
| if (*rest) |
| goto bad_val; |
| } else if (!strcmp(this_char,"gid")) { |
| if (!gid) |
| continue; |
| *gid = simple_strtoul(value,&rest,0); |
| if (*rest) |
| goto bad_val; |
| } else { |
| printk(KERN_ERR "tmpfs: Bad mount option %s\n", |
| this_char); |
| return 1; |
| } |
| } |
| return 0; |
| |
| bad_val: |
| printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", |
| value, this_char); |
| return 1; |
| } |
| |
| static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| unsigned long max_blocks = sbinfo->max_blocks; |
| unsigned long max_inodes = sbinfo->max_inodes; |
| |
| if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes)) |
| return -EINVAL; |
| return shmem_set_size(sbinfo, max_blocks, max_inodes); |
| } |
| |
| static int shmem_sync_file(struct file *file, struct dentry *dentry, int datasync) |
| { |
| return 0; |
| } |
| #endif |
| |
| static struct super_block *shmem_read_super(struct super_block *sb, void *data, int silent) |
| { |
| struct inode *inode; |
| struct dentry *root; |
| unsigned long blocks, inodes; |
| int mode = S_IRWXUGO | S_ISVTX; |
| uid_t uid = current->fsuid; |
| gid_t gid = current->fsgid; |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| struct sysinfo si; |
| |
| /* |
| * Per default we only allow half of the physical ram per |
| * tmpfs instance |
| */ |
| si_meminfo(&si); |
| blocks = inodes = si.totalram / 2; |
| |
| #ifdef CONFIG_TMPFS |
| if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, &inodes)) |
| return NULL; |
| #endif |
| |
| spin_lock_init(&sbinfo->stat_lock); |
| sbinfo->max_blocks = blocks; |
| sbinfo->free_blocks = blocks; |
| sbinfo->max_inodes = inodes; |
| sbinfo->free_inodes = inodes; |
| sb->s_maxbytes = SHMEM_MAX_BYTES; |
| sb->s_blocksize = PAGE_CACHE_SIZE; |
| sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
| sb->s_magic = TMPFS_MAGIC; |
| sb->s_op = &shmem_ops; |
| inode = shmem_get_inode(sb, S_IFDIR | mode, 0); |
| if (!inode) |
| return NULL; |
| |
| inode->i_uid = uid; |
| inode->i_gid = gid; |
| root = d_alloc_root(inode); |
| if (!root) { |
| iput(inode); |
| return NULL; |
| } |
| sb->s_root = root; |
| return sb; |
| } |
| |
| static struct address_space_operations shmem_aops = { |
| removepage: shmem_removepage, |
| writepage: shmem_writepage, |
| #ifdef CONFIG_TMPFS |
| readpage: shmem_readpage, |
| prepare_write: shmem_prepare_write, |
| commit_write: shmem_commit_write, |
| #endif |
| }; |
| |
| static struct file_operations shmem_file_operations = { |
| mmap: shmem_mmap, |
| #ifdef CONFIG_TMPFS |
| read: shmem_file_read, |
| write: shmem_file_write, |
| fsync: shmem_sync_file, |
| #endif |
| }; |
| |
| static struct inode_operations shmem_inode_operations = { |
| truncate: shmem_truncate, |
| setattr: shmem_notify_change, |
| }; |
| |
| static struct inode_operations shmem_dir_inode_operations = { |
| #ifdef CONFIG_TMPFS |
| create: shmem_create, |
| lookup: shmem_lookup, |
| link: shmem_link, |
| unlink: shmem_unlink, |
| symlink: shmem_symlink, |
| mkdir: shmem_mkdir, |
| rmdir: shmem_rmdir, |
| mknod: shmem_mknod, |
| rename: shmem_rename, |
| #endif |
| }; |
| |
| static struct super_operations shmem_ops = { |
| #ifdef CONFIG_TMPFS |
| statfs: shmem_statfs, |
| remount_fs: shmem_remount_fs, |
| #endif |
| delete_inode: shmem_delete_inode, |
| put_inode: force_delete, |
| }; |
| |
| static struct vm_operations_struct shmem_vm_ops = { |
| nopage: shmem_nopage, |
| }; |
| |
| #ifdef CONFIG_TMPFS |
| /* type "shm" will be tagged obsolete in 2.5 */ |
| static DECLARE_FSTYPE(shmem_fs_type, "shm", shmem_read_super, FS_LITTER); |
| static DECLARE_FSTYPE(tmpfs_fs_type, "tmpfs", shmem_read_super, FS_LITTER); |
| #else |
| static DECLARE_FSTYPE(tmpfs_fs_type, "tmpfs", shmem_read_super, FS_LITTER|FS_NOMOUNT); |
| #endif |
| static struct vfsmount *shm_mnt; |
| |
| static int __init init_tmpfs(void) |
| { |
| int error; |
| |
| error = register_filesystem(&tmpfs_fs_type); |
| if (error) { |
| printk(KERN_ERR "Could not register tmpfs\n"); |
| goto out3; |
| } |
| #ifdef CONFIG_TMPFS |
| error = register_filesystem(&shmem_fs_type); |
| if (error) { |
| printk(KERN_ERR "Could not register shm fs\n"); |
| goto out2; |
| } |
| devfs_mk_dir(NULL, "shm", NULL); |
| #endif |
| shm_mnt = kern_mount(&tmpfs_fs_type); |
| if (IS_ERR(shm_mnt)) { |
| error = PTR_ERR(shm_mnt); |
| printk(KERN_ERR "Could not kern_mount tmpfs\n"); |
| goto out1; |
| } |
| |
| /* The internal instance should not do size checking */ |
| shmem_set_size(SHMEM_SB(shm_mnt->mnt_sb), ULONG_MAX, ULONG_MAX); |
| return 0; |
| |
| out1: |
| #ifdef CONFIG_TMPFS |
| unregister_filesystem(&shmem_fs_type); |
| out2: |
| #endif |
| unregister_filesystem(&tmpfs_fs_type); |
| out3: |
| shm_mnt = ERR_PTR(error); |
| return error; |
| } |
| module_init(init_tmpfs) |
| |
| /* |
| * shmem_file_setup - get an unlinked file living in tmpfs |
| * |
| * @name: name for dentry (to be seen in /proc/<pid>/maps |
| * @size: size to be set for the file |
| * |
| */ |
| struct file *shmem_file_setup(char *name, loff_t size) |
| { |
| int error; |
| struct file *file; |
| struct inode *inode; |
| struct dentry *dentry, *root; |
| struct qstr this; |
| int vm_enough_memory(long pages); |
| |
| if (IS_ERR(shm_mnt)) |
| return (void *)shm_mnt; |
| |
| if (size > SHMEM_MAX_BYTES) |
| return ERR_PTR(-EINVAL); |
| |
| if (!vm_enough_memory(VM_ACCT(size))) |
| return ERR_PTR(-ENOMEM); |
| |
| this.name = name; |
| this.len = strlen(name); |
| this.hash = 0; /* will go */ |
| root = shm_mnt->mnt_root; |
| dentry = d_alloc(root, &this); |
| if (!dentry) |
| return ERR_PTR(-ENOMEM); |
| |
| error = -ENFILE; |
| file = get_empty_filp(); |
| if (!file) |
| goto put_dentry; |
| |
| error = -ENOSPC; |
| inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); |
| if (!inode) |
| goto close_file; |
| |
| d_instantiate(dentry, inode); |
| inode->i_size = size; |
| inode->i_nlink = 0; /* It is unlinked */ |
| file->f_vfsmnt = mntget(shm_mnt); |
| file->f_dentry = dentry; |
| file->f_op = &shmem_file_operations; |
| file->f_mode = FMODE_WRITE | FMODE_READ; |
| return file; |
| |
| close_file: |
| put_filp(file); |
| put_dentry: |
| dput(dentry); |
| return ERR_PTR(error); |
| } |
| |
| /* |
| * shmem_zero_setup - setup a shared anonymous mapping |
| * |
| * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
| */ |
| int shmem_zero_setup(struct vm_area_struct *vma) |
| { |
| struct file *file; |
| loff_t size = vma->vm_end - vma->vm_start; |
| |
| file = shmem_file_setup("dev/zero", size); |
| if (IS_ERR(file)) |
| return PTR_ERR(file); |
| |
| if (vma->vm_file) |
| fput(vma->vm_file); |
| vma->vm_file = file; |
| vma->vm_ops = &shmem_vm_ops; |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(shmem_file_setup); |