xfstests/011 failed in node with small_size filesystem.
Can be reproduced by following script:
DEV_LIST="/dev/vdd /dev/vde"
DEV_REPLACE="/dev/vdf"
do_test()
{
local mkfs_opt="$1"
local size="$2"
dmesg -c >/dev/null
umount $SCRATCH_MNT &>/dev/null
echo mkfs.btrfs -f $mkfs_opt "${DEV_LIST[*]}"
mkfs.btrfs -f $mkfs_opt "${DEV_LIST[@]}" || return 1
mount "${DEV_LIST[0]}" $SCRATCH_MNT
echo -n "Writing big files"
dd if=/dev/urandom of=$SCRATCH_MNT/t0 bs=1M count=1 >/dev/null 2>&1
for ((i = 1; i <= size; i++)); do
echo -n .
/bin/cp $SCRATCH_MNT/t0 $SCRATCH_MNT/t$i || return 1
done
echo
echo Start replace
btrfs replace start -Bf "${DEV_LIST[0]}" "$DEV_REPLACE" $SCRATCH_MNT || {
dmesg
return 1
}
return 0
}
# Set size to value near fs size
# for example, 1897 can trigger this bug in 2.6G device.
#
./do_test "-d raid1 -m raid1" 1897
System will report replace fail with following warning in dmesg:
[ 134.710853] BTRFS: dev_replace from /dev/vdd (devid 1) to /dev/vdf started
[ 135.542390] BTRFS: btrfs_scrub_dev(/dev/vdd, 1, /dev/vdf) failed -28
[ 135.543505] ------------[ cut here ]------------
[ 135.544127] WARNING: CPU: 0 PID: 4080 at fs/btrfs/dev-replace.c:428
btrfs_dev_replace_start+0x398/0x440()
[ 135.545276] Modules linked in:
[ 135.545681] CPU: 0 PID: 4080 Comm: btrfs Not tainted 4.3.0 #256
[ 135.546439] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
[ 135.547798] ffffffff81c5bfcf ffff88003cbb3d28 ffffffff817fe7b5
0000000000000000
[ 135.548774] ffff88003cbb3d60 ffffffff810a88f1 ffff88002b030000
00000000ffffffe4
[ 135.549774] ffff88003c080000 ffff88003c082588 ffff88003c28ab60
ffff88003cbb3d70
[ 135.550758] Call Trace:
[ 135.551086] [<ffffffff817fe7b5>] dump_stack+0x44/0x55
[ 135.551737] [<ffffffff810a88f1>] warn_slowpath_common+0x81/0xc0
[ 135.552487] [<ffffffff810a89e5>] warn_slowpath_null+0x15/0x20
[ 135.553211] [<ffffffff81448c88>] btrfs_dev_replace_start+0x398/0x440
[ 135.554051] [<ffffffff81412c3e>] btrfs_ioctl+0x1d2e/0x25c0
[ 135.554722] [<ffffffff8114c7ba>] ? __audit_syscall_entry+0xaa/0xf0
[ 135.555506] [<ffffffff8111ab36>] ? current_kernel_time64+0x56/0xa0
[ 135.556304] [<ffffffff81201e3d>] do_vfs_ioctl+0x30d/0x580
[ 135.557009] [<ffffffff8114c7ba>] ? __audit_syscall_entry+0xaa/0xf0
[ 135.557855] [<ffffffff810011d1>] ? do_audit_syscall_entry+0x61/0x70
[ 135.558669] [<ffffffff8120d1c1>] ? __fget_light+0x61/0x90
[ 135.559374] [<ffffffff81202124>] SyS_ioctl+0x74/0x80
[ 135.559987] [<ffffffff81809857>] entry_SYSCALL_64_fastpath+0x12/0x6f
[ 135.560842] ---[ end trace 2a5c1fc3205abbdd ]---
Reason:
When big data writen to fs, the whole free space will be allocated
for data chunk.
And operation as scrub need to set_block_ro(), and when there is
only one metadata chunk in system(or other metadata chunks
are all full), the function will try to allocate a new chunk,
and failed because no space in device.
Fix:
When set_block_ro failed for metadata chunk, it is not a problem
because scrub_lock paused commit_trancaction in same time, and
metadata are always cowed, so the on-the-fly writepages will not
write data into same place with scrub/replace.
Let replace continue in this case is no problem.
Tested by above script, and xfstests/011, plus 100 times xfstests/070.
Changelog v1->v2:
1: Add detail comments in source and commit-message.
2: Add dmesg detail into commit-message.
3: Limit return value of -ENOSPC to be passed.
All suggested by: Filipe Manana <fdman...@gmail.com>
Suggested-by: Filipe Manana <fdman...@gmail.com>
Signed-off-by: Zhao Lei <zhao...@cn.fujitsu.com>
---
fs/btrfs/scrub.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index a39f5d1..fc0bb91 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3532,6 +3532,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
u64 length;
u64 chunk_offset;
int ret = 0;
+ int ro_set;
int slot;
struct extent_buffer *l;
struct btrfs_key key;
@@ -3617,7 +3618,21 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
scrub_pause_on(fs_info);
ret = btrfs_inc_block_group_ro(root, cache);
scrub_pause_off(fs_info);
- if (ret) {
+
+ if (ret == 0) {
+ ro_set = 1;
+ } else if (ret == -ENOSPC) {
+ /*
+ * btrfs_inc_block_group_ro return -ENOSPC when it
+ * failed in creating new chunk for metadata.
+ * It is not a problem for scrub/replace, because
+ * metadata are always cowed, and our scrub paused
+ * commit_transactions.
+ */
+ ro_set = 0;
+ } else {
+ btrfs_warn(fs_info, "failed setting block group ro,
ret=%d\n",
+ ret);
btrfs_put_block_group(cache);
break;
}
@@ -3660,7 +3675,8 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
scrub_pause_off(fs_info);
- btrfs_dec_block_group_ro(root, cache);
+ if (ro_set)
+ btrfs_dec_block_group_ro(root, cache);
btrfs_put_block_group(cache);
if (ret)
--
1.8.5.1
--
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