2009-10-13 02:34:59

by Eric Sandeen

Subject: [PATCH] ext3: retry failed direct IO allocations

On a 256M 4k block filesystem, doing this in a loop:

dd if=/dev/zero of=test oflag=direct bs=1M count=64
rm -f test

eventually leads to spurious ENOSPC:

dd: writing `test': No space left on device

As with other block allocation callers, it looks like we need to
potentially retry the allocations on the initial ENOSPC.

A similar patch went into ext4 (commit
fbbf69456619de5d251cb9f1df609069178c62d5)

Signed-off-by: Eric Sandeen <[email protected]>
---

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index acf1b14..069a163 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -1735,6 +1735,7 @@ static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
ssize_t ret;
int orphan = 0;
size_t count = iov_length(iov, nr_segs);
+ int retries = 0;

if (rw == WRITE) {
loff_t final_size = offset + count;
@@ -1757,9 +1758,12 @@ static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
}
}

+retry:
ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
offset, nr_segs,
ext3_get_block, NULL);
+ if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
+ goto retry;

if (orphan) {
int err;

2009-10-14 12:53:56

by Jan Kara

Subject: Re: [PATCH] ext3: retry failed direct IO allocations

On Mon 12-10-09 21:34:27, Eric Sandeen wrote:
> On a 256M 4k block filesystem, doing this in a loop:
>
> dd if=/dev/zero of=test oflag=direct bs=1M count=64
> rm -f test
>
> eventually leads to spurious ENOSPC:
>
> dd: writing `test': No space left on device
>
> As with other block allocation callers, it looks like we need to
> potentially retry the allocations on the initial ENOSPC.
>
> A similar patch went into ext4 (commit
> fbbf69456619de5d251cb9f1df609069178c62d5)
Thanks for the patch Eric. Committed to my tree.

Honza

> ---
>
> diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
> index acf1b14..069a163 100644
> --- a/fs/ext3/inode.c
> +++ b/fs/ext3/inode.c
> @@ -1735,6 +1735,7 @@ static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
> ssize_t ret;
> int orphan = 0;
> size_t count = iov_length(iov, nr_segs);
> + int retries = 0;
>
> if (rw == WRITE) {
> loff_t final_size = offset + count;
> @@ -1757,9 +1758,12 @@ static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
> }
> }
>
> +retry:
> ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
> offset, nr_segs,
> ext3_get_block, NULL);
> + if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
> + goto retry;
>
> if (orphan) {
> int err;
>
--
Jan Kara <[email protected]>
SUSE Labs, CR