From: Ethan Lien ethanlien@synology.com
commit b642b52d0b50f4d398cb4293f64992d0eed2e2ce upstream.
We use extent_changeset->bytes_changed in qgroup_reserve_data() to record how many bytes we set for EXTENT_QGROUP_RESERVED state. Currently the bytes_changed is set as "unsigned int", and it will overflow if we try to fallocate a range larger than 4GiB. The result is we reserve less bytes and eventually break the qgroup limit.
Unlike regular buffered/direct write, which we use one changeset for each ordered extent, which can never be larger than 256M. For fallocate, we use one changeset for the whole range, thus it no longer respects the 256M per extent limit, and caused the problem.
The following example test script reproduces the problem:
$ cat qgroup-overflow.sh #!/bin/bash
DEV=/dev/sdj MNT=/mnt/sdj
mkfs.btrfs -f $DEV mount $DEV $MNT
# Set qgroup limit to 2GiB. btrfs quota enable $MNT btrfs qgroup limit 2G $MNT
# Try to fallocate a 3GiB file. This should fail. echo echo "Try to fallocate a 3GiB file..." fallocate -l 3G $MNT/3G.file
# Try to fallocate a 5GiB file. echo echo "Try to fallocate a 5GiB file..." fallocate -l 5G $MNT/5G.file
# See we break the qgroup limit. echo sync btrfs qgroup show -r $MNT
umount $MNT
When running the test:
$ ./qgroup-overflow.sh (...)
Try to fallocate a 3GiB file... fallocate: fallocate failed: Disk quota exceeded
Try to fallocate a 5GiB file...
qgroupid rfer excl max_rfer -------- ---- ---- -------- 0/5 5.00GiB 5.00GiB 2.00GiB
Since we have no control of how bytes_changed is used, it's better to set it to u64.
CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Qu Wenruo wqu@suse.com Signed-off-by: Ethan Lien ethanlien@synology.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/extent_io.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -121,7 +121,7 @@ struct extent_buffer { */ struct extent_changeset { /* How many bytes are set/cleared in this operation */ - unsigned int bytes_changed; + u64 bytes_changed;
/* Changed ranges */ struct ulist range_changed;