| From 51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2 Mon Sep 17 00:00:00 2001 |
| From: Theodore Ts'o <tytso@mit.edu> |
| Date: Fri, 6 Oct 2017 23:09:55 -0400 |
| Subject: ext4: fix interaction between i_size, fallocate, and delalloc after a crash |
| |
| From: Theodore Ts'o <tytso@mit.edu> |
| |
| commit 51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2 upstream. |
| |
| If there are pending writes subject to delayed allocation, then i_size |
| will show size after the writes have completed, while i_disksize |
| contains the value of i_size on the disk (since the writes have not |
| been persisted to disk). |
| |
| If fallocate(2) is called with the FALLOC_FL_KEEP_SIZE flag, either |
| with or without the FALLOC_FL_ZERO_RANGE flag set, and the new size |
| after the fallocate(2) is between i_size and i_disksize, then after a |
| crash, if a journal commit has resulted in the changes made by the |
| fallocate() call to be persisted after a crash, but the delayed |
| allocation write has not resolved itself, i_size would not be updated, |
| and this would cause the following e2fsck complaint: |
| |
| Inode 12, end of extent exceeds allowed value |
| (logical block 33, physical block 33441, len 7) |
| |
| This can only take place on a sparse file, where the fallocate(2) call |
| is allocating blocks in a range which is before a pending delayed |
| allocation write which is extending i_size. Since this situation is |
| quite rare, and the window in which the crash must take place is |
| typically < 30 seconds, in practice this condition will rarely happen. |
| |
| Nevertheless, it can be triggered in testing, and in particular by |
| xfstests generic/456. |
| |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Reported-by: Amir Goldstein <amir73il@gmail.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/extents.c | 6 ++++-- |
| 1 file changed, 4 insertions(+), 2 deletions(-) |
| |
| --- a/fs/ext4/extents.c |
| +++ b/fs/ext4/extents.c |
| @@ -4807,7 +4807,8 @@ static long ext4_zero_range(struct file |
| } |
| |
| if (!(mode & FALLOC_FL_KEEP_SIZE) && |
| - offset + len > i_size_read(inode)) { |
| + (offset + len > i_size_read(inode) || |
| + offset + len > EXT4_I(inode)->i_disksize)) { |
| new_size = offset + len; |
| ret = inode_newsize_ok(inode, new_size); |
| if (ret) |
| @@ -4951,7 +4952,8 @@ long ext4_fallocate(struct file *file, i |
| } |
| |
| if (!(mode & FALLOC_FL_KEEP_SIZE) && |
| - offset + len > i_size_read(inode)) { |
| + (offset + len > i_size_read(inode) || |
| + offset + len > EXT4_I(inode)->i_disksize)) { |
| new_size = offset + len; |
| ret = inode_newsize_ok(inode, new_size); |
| if (ret) |