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authorGoldwyn Rodrigues <rgoldwyn@suse.com>2016-09-30 10:40:52 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-11-18 10:48:37 +0100
commitee5dd6878886aa50f865ca10b9753bce2830e062 (patch)
parentae6d4df4a7a06075c3fbc7d80cededcccb908e06 (diff)
btrfs: qgroup: Prevent qgroup->reserved from going subzero
commit 0b34c261e235a5c74dcf78bd305845bd15fe2b42 upstream. While free'ing qgroup->reserved resources, we much check if the page has not been invalidated by a truncate operation by checking if the page is still dirty before reducing the qgroup resources. Resources in such a case are free'd when the entire extent is released by delayed_ref. This fixes a double accounting while releasing resources in case of truncating a file, reproduced by the following testcase. SCRATCH_DEV=/dev/vdb SCRATCH_MNT=/mnt mkfs.btrfs -f $SCRATCH_DEV mount -t btrfs $SCRATCH_DEV $SCRATCH_MNT cd $SCRATCH_MNT btrfs quota enable $SCRATCH_MNT btrfs subvolume create a btrfs qgroup limit 500m a $SCRATCH_MNT sync for c in {1..15}; do dd if=/dev/zero bs=1M count=40 of=$SCRATCH_MNT/a/file; done sleep 10 sync sleep 5 touch $SCRATCH_MNT/a/newfile echo "Removing file" rm $SCRATCH_MNT/a/file Fixes: b9d0b38928 ("btrfs: Add handler for invalidate page") Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4bc9dbf29a73..3cff6523f27d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8691,9 +8691,14 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset,
* So even we call qgroup_free_data(), it won't decrease reserved
* space.
* 2) Not written to disk
- * This means the reserved space should be freed here.
+ * This means the reserved space should be freed here. However,
+ * if a truncate invalidates the page (by clearing PageDirty)
+ * and the page is accounted for while allocating extent
+ * in btrfs_check_data_free_space() we let delayed_ref to
+ * free the entire extent.
- btrfs_qgroup_free_data(inode, page_start, PAGE_CACHE_SIZE);
+ if (PageDirty(page))
+ btrfs_qgroup_free_data(inode, page_start, PAGE_SIZE);
if (!inode_evicting) {
clear_extent_bit(tree, page_start, page_end,