From: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
Btrfs will report NO_SPACE when we create and remove files for several times,
and we can't write to filesystem until mount it again.
Steps to reproduce:
1: Create a single-dev btrfs fs with default option
2: Write a file into it to take up most fs space
3: Delete above file
4: Wait about 100s to let chunk removed
5: goto 2
Script is like following:
#!/bin/bash
# Recommend 1.2G space, too large disk will make test slow
DEV="/dev/sda16"
MNT="/mnt/tmp"
dev_size="$(lsblk -bn -o SIZE "$DEV")" || exit 2
file_size_m=$((dev_size * 75 / 100 / 1024 / 1024))
echo "Loop write ${file_size_m}M file on $((dev_size / 1024 / 1024))M dev"
for ((i = 0; i < 10; i++)); do umount "$MNT" 2>/dev/null; done
echo "mkfs $DEV"
mkfs.btrfs -f "$DEV" >/dev/null || exit 2
echo "mount $DEV $MNT"
mount "$DEV" "$MNT" || exit 2
for ((loop_i = 0; loop_i < 20; loop_i++)); do
echo
echo "loop $loop_i"
echo "dd file..."
cmd=(dd if=/dev/zero of="$MNT"/file0 bs=1M count="$file_size_m")
"${cmd[@]}" 2>/dev/null || {
# NO_SPACE error triggered
echo "dd failed: ${cmd[*]}"
exit 1
}
echo "rm file..."
rm -f "$MNT"/file0 || exit 2
for ((i = 0; i < 10; i++)); do
df "$MNT" | tail -1
sleep 10
done
done
Reason:
It is triggered by commit: 47ab2a6c689913db23ccae38349714edf8365e0a
which is used to remove empty block groups automatically, but the
reason is not in that patch. Code before works well because btrfs
don't need to create and delete chunks so many times with high
complexity.
Above bug is caused by many reason, any of them can trigger it.
Reason1:
btrfs_check_data_free_space() try to commit transaction and retry
allocating chunk when the first allocating failed, but space_info->full
is set in first allocating, and prevent second allocating in retry.
When we commit transaction with removed bgs, we need to clear
space_info->full.
Fixed in this patch.
Reason2:
When we remove some continuous chunks but leave other chunks after,
these disk space should be used by chunk-recreating, but in current
code, only first create will successed.
Fixed by Forrest Liu <forrestl@xxxxxxxxxxxx> in:
Btrfs: fix find_free_dev_extent() malfunction in case device tree has hole
Reason3:
contains_pending_extent() return wrong value in calculation.
Fixed by Forrest Liu <forrestl@xxxxxxxxxxxx> in:
Btrfs: fix find_free_dev_extent() malfunction in case device tree has hole
Changelog v2->v3:
v2 fixed the bug by adding more commit-transaction, but we
only need to reclaim space when we are really have no space for
new chunk.
Actually, code already have this type of commit-and-retry, we only
need to make it working with removed-bgs.
v3 fixed the bug by above way.
Changelog v1->v2:
v1 will introduce a new bug when delete and create chunk in same disk
space in same transaction, noticed by:
Filipe David Manana <fdmanana@xxxxxxxxx>
V2 fix this bug by commit transaction after remove block grops.
Tested for severial times by above script.
Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
---
fs/btrfs/transaction.c | 4 ++++
fs/btrfs/transaction.h | 5 +++++
fs/btrfs/volumes.c | 2 ++
3 files changed, 11 insertions(+)
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 8cc0e97..f9299f3 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -220,6 +220,7 @@ loop:
* commit the transaction.
*/
atomic_set(&cur_trans->use_count, 2);
+ atomic_set(&cur_trans->have_free_bgs, 0);
cur_trans->start_time = get_seconds();
cur_trans->delayed_refs.href_root = RB_ROOT;
@@ -2030,6 +2031,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
btrfs_finish_extent_commit(trans, root);
+ if (atomic_read(&cur_trans->have_free_bgs))
+ btrfs_clear_space_info_full(root->fs_info);
+
root->fs_info->last_trans_committed = cur_trans->transid;
/*
* We needn't acquire the lock here because there is no other task
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 00ed29c..5225326 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -47,6 +47,11 @@ struct btrfs_transaction {
atomic_t num_writers;
atomic_t use_count;
+ /*
+ * true if there is free bgs operations in this transaction
+ */
+ atomic_t have_free_bgs;
+
/* Be protected by fs_info->trans_lock when we want to change it. */
enum btrfs_trans_state state;
struct list_head list;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index ba9857d..46495a1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1323,6 +1323,8 @@ again:
if (ret) {
btrfs_error(root->fs_info, ret,
"Failed to remove dev extent item");
+ } else {
+ atomic_set(&trans->transaction->have_free_bgs, 1);
}
out:
btrfs_free_path(path);
--
1.8.5.1
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