On Fri 16-06-17 15:34:10, Jeff Layton wrote:
> Resetting this flag is almost certainly racy, and will be problematic
> with some coming changes.
>
> Make filemap_fdatawait_keep_errors return int, but not clear the flag(s).
> Have jbd2 call it instead of filemap_fdatawait and don't attempt to
> re-set the error flag if it fails.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/jbd2/commit.c | 15 +++------------
> include/linux/fs.h | 2 +-
> mm/filemap.c | 16 ++++++++++++++--
> 3 files changed, 18 insertions(+), 15 deletions(-)
>
> diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
> index b6b194ec1b4f..502110540598 100644
> --- a/fs/jbd2/commit.c
> +++ b/fs/jbd2/commit.c
> @@ -263,18 +263,9 @@ static int journal_finish_inode_data_buffers(journal_t *journal,
> continue;
> jinode->i_flags |= JI_COMMIT_RUNNING;
> spin_unlock(&journal->j_list_lock);
> - err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping);
> - if (err) {
> - /*
> - * Because AS_EIO is cleared by
> - * filemap_fdatawait_range(), set it again so
> - * that user process can get -EIO from fsync().
> - */
> - mapping_set_error(jinode->i_vfs_inode->i_mapping, -EIO);
> -
> - if (!ret)
> - ret = err;
> - }
> + err = filemap_fdatawait_keep_errors(jinode->i_vfs_inode->i_mapping);
> + if (!ret)
> + ret = err;
> spin_lock(&journal->j_list_lock);
> jinode->i_flags &= ~JI_COMMIT_RUNNING;
> smp_mb();
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 1a135274b4f8..1b1233a1db1e 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2509,7 +2509,7 @@ extern int write_inode_now(struct inode *, int);
> extern int filemap_fdatawrite(struct address_space *);
> extern int filemap_flush(struct address_space *);
> extern int filemap_fdatawait(struct address_space *);
> -extern void filemap_fdatawait_keep_errors(struct address_space *);
> +extern int filemap_fdatawait_keep_errors(struct address_space *);
> extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
> loff_t lend);
> extern int filemap_write_and_wait(struct address_space *mapping);
> diff --git a/mm/filemap.c b/mm/filemap.c
> index b9e870600572..37f286df7c95 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -311,6 +311,16 @@ int filemap_check_errors(struct address_space *mapping)
> }
> EXPORT_SYMBOL(filemap_check_errors);
>
> +static int filemap_check_and_keep_errors(struct address_space *mapping)
> +{
> + /* Check for outstanding write errors */
> + if (test_bit(AS_EIO, &mapping->flags))
> + return -EIO;
> + if (test_bit(AS_ENOSPC, &mapping->flags))
> + return -ENOSPC;
> + return 0;
> +}
> +
> /**
> * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
> * @mapping: address space structure to write
> @@ -455,15 +465,17 @@ EXPORT_SYMBOL(filemap_fdatawait_range);
> * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
> * fsfreeze(8)
> */
> -void filemap_fdatawait_keep_errors(struct address_space *mapping)
> +int filemap_fdatawait_keep_errors(struct address_space *mapping)
> {
> loff_t i_size = i_size_read(mapping->host);
>
> if (i_size == 0)
> - return;
> + return 0;
>
> __filemap_fdatawait_range(mapping, 0, i_size - 1);
> + return filemap_check_and_keep_errors(mapping);
> }
> +EXPORT_SYMBOL(filemap_fdatawait_keep_errors);
>
> /**
> * filemap_fdatawait - wait for all under-writeback pages to complete
> --
> 2.13.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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