From a348c8d4f6cf23ef04b0edaccdfe9d94c2d335db Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Wed, 2 Nov 2022 12:46:35 +0000 Subject: [PATCH] btrfs: fix nowait buffered write returning -ENOSPC If we are doing a buffered write in NOWAIT context and we can't reserve metadata space due to -ENOSPC, then we should return -EAGAIN so that we retry the write in a context allowed to block and do metadata reservation with flushing, which might succeed this time due to the allowed flushing. Returning -ENOSPC while in NOWAIT context simply makes some writes fail with -ENOSPC when they would likely succeed after switching from NOWAIT context to blocking context. That is unexpected behaviour and even fio complains about it with a warning like this: fio: io_u error on file /mnt/sdi/task_0.0.0: No space left on device: write offset=1535705088, buflen=65536 fio: pid=592630, err=28/file:io_u.c:1846, func=io_u error, error=No space left on device The fio's job config is this: [global] bs=64K ioengine=io_uring iodepth=1 size=2236962133 nr_files=1 filesize=2236962133 direct=0 runtime=10 fallocate=posix io_size=2236962133 group_reporting time_based [task_0] rw=randwrite directory=/mnt/sdi numjobs=4 So fix this by returning -EAGAIN if we are in NOWAIT context and the metadata reservation failed with -ENOSPC. Fixes: 304e45acdb8f ("btrfs: plumb NOWAIT through the write path") Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/file.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index d55ad46384d1..5ce2ae9d4f72 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1598,6 +1598,9 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, write_bytes); else btrfs_check_nocow_unlock(BTRFS_I(inode)); + + if (nowait && ret == -ENOSPC) + ret = -EAGAIN; break; }