Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 080/276] Btrfs: fix data bytes_may_use underflow with fallocate due to failed quota reserve | Date | Wed, 29 May 2019 20:03:58 -0700 |
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[ Upstream commit 39ad317315887c2cb9a4347a93a8859326ddf136 ]
When doing fallocate, we first add the range to the reserve_list and then reserve the quota. If quota reservation fails, we'll release all reserved parts of reserve_list.
However, cur_offset is not updated to indicate that this range is already been inserted into the list. Therefore, the same range is freed twice. Once at list_for_each_entry loop, and once at the end of the function. This will result in WARN_ON on bytes_may_use when we free the remaining space.
At the end, under the 'out' label we have a call to:
btrfs_free_reserved_data_space(inode, data_reserved, alloc_start, alloc_end - cur_offset);
The start offset, third argument, should be cur_offset.
Everything from alloc_start to cur_offset was freed by the list_for_each_entry_safe_loop.
Fixes: 18513091af94 ("btrfs: update btrfs_space_info's bytes_may_use timely") Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Robbie Ko <robbieko@synology.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/btrfs/file.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index de4d3baec1616..e24c0a69ff5d4 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -3161,6 +3161,7 @@ static long btrfs_fallocate(struct file *file, int mode, ret = btrfs_qgroup_reserve_data(inode, &data_reserved, cur_offset, last_byte - cur_offset); if (ret < 0) { + cur_offset = last_byte; free_extent_map(em); break; } @@ -3210,7 +3211,7 @@ static long btrfs_fallocate(struct file *file, int mode, /* Let go of our reservation. */ if (ret != 0 && !(mode & FALLOC_FL_ZERO_RANGE)) btrfs_free_reserved_data_space(inode, data_reserved, - alloc_start, alloc_end - cur_offset); + cur_offset, alloc_end - cur_offset); extent_changeset_free(data_reserved); return ret; } -- 2.20.1
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