Re: No space left on device (28)

[Josef Bacik <jbacik@fusionio.com>]

On Tue, Mar 26, 2013 at 06:55:23AM -0600, Stefan Priebe - Profihost AG wrote:
> Hi Josef,
> 
> Am 26.03.2013 13:53, schrieb Josef Bacik:
> > On Tue, Mar 26, 2013 at 01:45:42AM -0600, Stefan Priebe wrote:
> >> Hi,
> >>
> >> output here:
> >> [  590.546162] returning enospc, space_info 3, size 0 reserved 0, flush 
> >> 2, flush_state 7  dumping space info
> >> [  590.548280] space_info 4 has 6439292928 free, is full
> >> [  590.548283] space_info total=25748307968, used=19308916736, pinned=0, 
> >> reserved=32768, may_use=6438354944, readonly=65536
> >> [  590.550147] returning enospc, space_info 3, size 0 reserved 0, flush 
> >> 2, flush_state 7  dumping space info
> >> [  590.552264] space_info 4 has 6439284736 free, is full
> >> [  590.552267] space_info total=25748307968, used=19308916736, pinned=0, 
> >> reserved=40960, may_use=6438354944, readonly=65536
> >> [  590.554141] returning enospc, space_info 3, size 0 reserved 0, flush 
> >> 2, flush_state 7  dumping space info
> >> [  590.556258] space_info 4 has 6439284736 free, is full
> >> [  590.556261] space_info total=25748307968, used=19308916736, pinned=0, 
> >> reserved=40960, may_use=6438354944, readonly=65536
> >> [  591.145255] returning enospc, space_info 3, size 0 reserved 0, flush 
> >> 2, flush_state 7  dumping space info
> >> [  591.147373] space_info 4 has 6439235584 free, is full
> >> [  591.147375] space_info total=25748307968, used=19308916736, pinned=0, 
> >> reserved=90112, may_use=6438354944, readonly=65536
> >> [  595.560257] returning enospc, space_info 3, size 0 reserved 0, flush 
> >> 2, flush_state 7  dumping space info
> >> [  595.562390] space_info 4 has 6439120896 free, is full
> >> [  595.562393] space_info total=25748307968, used=19309047808, pinned=0, 
> >> reserved=73728, may_use=6438297600, readonly=65536
> >>
> > 
> > Weird, we have all the flushing stuff set and yet there is still a whole lot of
> > outstanding reservations.  Do you have compression enabled?  Thanks,
> 
> no - it's just mounted with mount -o noatime
> 
> :~# cat /proc/mounts | grep btrfs
> /dev/mapper/raid54tb1 /mnt btrfs rw,noatime,space_cache 0 0
>

Ok I think I see what's going on.  Can you try this patch and see if it fixes
it?  Thanks,

Josef

 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index bf6433f..84e8909 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3803,6 +3803,19 @@ static int can_overcommit(struct btrfs_root *root,
 	return 0;
 }
 
+static int btrfs_try_writeback(struct super_block *sb, unsigned long nr_pages,
+			       enum wb_reason reason)
+{
+	if (!writeback_in_progress(sb->s_bdi) &&
+	    down_read_trylock(&sb->s_umount)) {
+		writeback_inodes_sb_nr(sb, nr_pages, reason);
+		up_read(&sb->s_umount);
+		return 1;
+	}
+
+	return 0;
+}
+
 void btrfs_writeback_inodes_sb_nr(struct btrfs_root *root,
 				  unsigned long nr_pages)
 {
@@ -3810,8 +3823,7 @@ void btrfs_writeback_inodes_sb_nr(struct btrfs_root *root,
 	int started;
 
 	/* If we can not start writeback, just sync all the delalloc file. */
-	started = try_to_writeback_inodes_sb_nr(sb, nr_pages,
-						      WB_REASON_FS_FREE_SPACE);
+	started = btrfs_try_writeback(sb, nr_pages, WB_REASON_FS_FREE_SPACE);
 	if (!started) {
 		/*
 		 * We needn't worry the filesystem going from r/w to r/o though
-- 
1.7.7.6