This is a note to let you know that I've just added the patch titled
ext4: fix interaction between i_size, fallocate, and delalloc after a crash
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: ext4-fix-interaction-between-i_size-fallocate-and-delalloc-after-a-crash.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
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 @@ -4803,7 +4803,8 @@ 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) @@ -4974,7 +4975,8 @@ 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)
Patches currently in stable-queue which might be from tytso@mit.edu are
queue-4.9/ext4-fix-interaction-between-i_size-fallocate-and-delalloc-after-a-crash.patch