Commit 3d3727cd authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds

mm, fadvise: don't return -EINVAL when filesystem cannot implement fadvise()

Eric Wong reported his test suite failex when /tmp is tmpfs.

https://lkml.org/lkml/2012/2/24/479

Currentlt the input check of POSIX_FADV_WILLNEED has two problems.

- requires a_ops->readpage.  But in fact, force_page_cache_readahead()
  requires that the target filesystem has either ->readpage or ->readpages.

- returns -EINVAL when the filesystem doesn't have ->readpage.  But
  posix says that fadvise is merely a hint.  Thus fadvise() should return
  0 if filesystem has no means of implementing fadvise().  The userland
  application should not know nor care whcih type of filesystem backs the
  TMPDIR directory, as Eric pointed out.  There is nothing which userspace
  can do to solve this error.

So change the return value to 0 when filesytem doesn't support readahead.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: default avatarEric Wong <normalperson@yhbt.net>
Tested-by: default avatarEric Wong <normalperson@yhbt.net>
Reviewed-by: default avatarWanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c59e2610
......@@ -93,11 +93,6 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_WILLNEED:
if (!mapping->a_ops->readpage) {
ret = -EINVAL;
break;
}
/* First and last PARTIAL page! */
start_index = offset >> PAGE_CACHE_SHIFT;
end_index = endbyte >> PAGE_CACHE_SHIFT;
......@@ -107,11 +102,12 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
if (!nrpages)
nrpages = ~0UL;
ret = force_page_cache_readahead(mapping, file,
start_index,
/*
* Ignore return value because fadvise() shall return
* success even if filesystem can't retrieve a hint,
*/
force_page_cache_readahead(mapping, file, start_index,
nrpages);
if (ret > 0)
ret = 0;
break;
case POSIX_FADV_NOREUSE:
break;
......
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