On Thu 11-04-13 16:47:59, Dmitry Monakhov wrote:
> There are two convenient ways to report errors to userspace
> 1) retun error to original syscall for example write(2)
> 2) mark mapping with error flag and return it on later fsync(2)
>
> Second one is broken if (mapping->nrpages == 0)
> This is real-life situation because after error pages are likey
> to be truncated or invalidated.
>
> We have to return an error regardless to number of pages in the mapping.
>
> #Original testcase: git@xxxxxxxxxx:dmonakhov/xfstests.git
> MOUNT_OPTIONS="-b1024"
> ./check shared/305
Makes sence to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
BTW, this more belongs to the mm area so Andrew Morton might be the right
person to merge this. Added to CC.
Honza
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> ---
> mm/filemap.c | 29 +++++++++++++++++++++--------
> 1 files changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index e1979fd..ca47f0b 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -184,6 +184,17 @@ static int sleep_on_page_killable(void *word)
> return fatal_signal_pending(current) ? -EINTR : 0;
> }
>
> +static int filemap_check_errors(struct address_space *mapping)
> +{
> + int ret = 0;
> + /* Check for outstanding write errors */
> + if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
> + ret = -ENOSPC;
> + if (test_and_clear_bit(AS_EIO, &mapping->flags))
> + ret = -EIO;
> + return ret;
> +}
> +
> /**
> * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
> * @mapping: address space structure to write
> @@ -265,10 +276,10 @@ int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
> pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
> struct pagevec pvec;
> int nr_pages;
> - int ret = 0;
> + int ret2, ret = 0;
>
> if (end_byte < start_byte)
> - return 0;
> + goto out;
>
> pagevec_init(&pvec, 0);
> while ((index <= end) &&
> @@ -291,12 +302,10 @@ int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
> pagevec_release(&pvec);
> cond_resched();
> }
> -
> - /* Check for outstanding write errors */
> - if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
> - ret = -ENOSPC;
> - if (test_and_clear_bit(AS_EIO, &mapping->flags))
> - ret = -EIO;
> +out:
> + ret2 = filemap_check_errors(mapping);
> + if (!ret)
> + ret = ret2;
>
> return ret;
> }
> @@ -337,6 +346,8 @@ int filemap_write_and_wait(struct address_space *mapping)
> if (!err)
> err = err2;
> }
> + } else {
> + err = filemap_check_errors(mapping);
> }
> return err;
> }
> @@ -368,6 +379,8 @@ int filemap_write_and_wait_range(struct address_space *mapping,
> if (!err)
> err = err2;
> }
> + } else {
> + err = filemap_check_errors(mapping);
> }
> return err;
> }
> --
> 1.7.1
>
> --
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--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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