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btrfs: Fix NO_SPACE bug caused by delayed-iput 

Steps to reproduce:
  while true; do
    dd if=/dev/zero of=/btrfs_dir/file count=[fs_size * 75%]
    rm /btrfs_dir/file
    sync
  done

  And we'll see dd failed because btrfs return NO_SPACE.

Reason:
  Normally, btrfs_commit_transaction() call btrfs_run_delayed_iputs()
  in end to free fs space for next write, but sometimes it hadn't
  done work on time, because btrfs-cleaner thread get delayed-iputs
  from list before, but do iput() after next write.

  This is log:
  [ 2569.050776] comm=btrfs-cleaner func=btrfs_evict_inode() begin

  [ 2569.084280] comm=sync func=btrfs_commit_transaction() call btrfs_run_delayed_iputs()
  [ 2569.085418] comm=sync func=btrfs_commit_transaction() done btrfs_run_delayed_iputs()
  [ 2569.087554] comm=sync func=btrfs_commit_transaction() end

  [ 2569.191081] comm=dd begin
  [ 2569.790112] comm=dd func=__btrfs_buffered_write() ret=-28

  [ 2569.847479] comm=btrfs-cleaner func=add_pinned_bytes() 0 + 32677888 = 32677888
  [ 2569.849530] comm=btrfs-cleaner func=add_pinned_bytes() 32677888 + 23834624 = 56512512
  ...
  [ 2569.903893] comm=btrfs-cleaner func=add_pinned_bytes() 943976448 + 21762048 = 965738496
  [ 2569.908270] comm=btrfs-cleaner func=btrfs_evict_inode() end

Fix:
  Make btrfs_commit_transaction() wait current running btrfs-cleaner's
  delayed-iputs() done in end.

Test:
  Use script similar to above(more complex),
  before patch:
    7 failed in 100 * 20 loop.
  after patch:
    0 failed in 100 * 20 loop.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Zhao Lei 2015-02-26 10:49:20 +08:00 committed by Chris Mason
parent 18d018ad2c
commit d7c151717a
4 changed files with 13 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/btrfs/ctree.h
View File

@ -1538,6 +1538,7 @@ struct btrfs_fs_info {
spinlock_t delayed_iput_lock;
struct list_head delayed_iputs;
struct rw_semaphore delayed_iput_sem;
/* this protects tree_mod_seq_list */
spinlock_t tree_mod_seq_lock;

3
fs/btrfs/disk-io.c
View File

@ -2487,11 +2487,12 @@ int open_ctree(struct super_block *sb,
spin_lock_init(&fs_info->qgroup_op_lock);
spin_lock_init(&fs_info->buffer_lock);
spin_lock_init(&fs_info->unused_bgs_lock);
mutex_init(&fs_info->unused_bg_unpin_mutex);
rwlock_init(&fs_info->tree_mod_log_lock);
mutex_init(&fs_info->unused_bg_unpin_mutex);
mutex_init(&fs_info->reloc_mutex);
mutex_init(&fs_info->delalloc_root_mutex);
seqlock_init(&fs_info->profiles_lock);
init_rwsem(&fs_info->delayed_iput_sem);
init_completion(&fs_info->kobj_unregister);
INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);

6
fs/btrfs/extent-tree.c
View File

@ -3950,6 +3950,12 @@ commit_trans:
ret = btrfs_commit_transaction(trans, root);
if (ret)
return ret;
/*
* make sure that all running delayed iput are
* done
*/
down_write(&root->fs_info->delayed_iput_sem);
up_write(&root->fs_info->delayed_iput_sem);
goto again;
} else {
btrfs_end_transaction(trans, root);

4
fs/btrfs/inode.c
View File

@ -3111,6 +3111,8 @@ void btrfs_run_delayed_iputs(struct btrfs_root *root)
if (empty)
return;
down_read(&fs_info->delayed_iput_sem);
spin_lock(&fs_info->delayed_iput_lock);
list_splice_init(&fs_info->delayed_iputs, &list);
spin_unlock(&fs_info->delayed_iput_lock);
@ -3121,6 +3123,8 @@ void btrfs_run_delayed_iputs(struct btrfs_root *root)
iput(delayed->inode);
kfree(delayed);
}
up_read(&root->fs_info->delayed_iput_sem);
}
/*