The patch titled
Subject: mm, fadvise: don't return -EINVAL when filesystem cannot implement fadvise()
has been added to the -mm tree. Its filename is
mm-fadvise-dont-return-einval-when-filesystem-cannot-implement-fadvise.patch
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From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Subject: 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.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Hillf Danton <dhillf@xxxxxxxxx>
Signed-off-by: Eric Wong <normalperson@xxxxxxxx>
Tested-by: Eric Wong <normalperson@xxxxxxxx>
Reviewed-by: Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/fadvise.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
diff -puN mm/fadvise.c~mm-fadvise-dont-return-einval-when-filesystem-cannot-implement-fadvise mm/fadvise.c
--- a/mm/fadvise.c~mm-fadvise-dont-return-einval-when-filesystem-cannot-implement-fadvise
+++ a/mm/fadvise.c
@@ -93,11 +93,6 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, lof
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;
@@ -106,12 +101,13 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, lof
nrpages = end_index - start_index + 1;
if (!nrpages)
nrpages = ~0UL;
-
- ret = force_page_cache_readahead(mapping, file,
- start_index,
- nrpages);
- if (ret > 0)
- ret = 0;
+
+ /*
+ * 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);
break;
case POSIX_FADV_NOREUSE:
break;
_
Subject: Subject: mm, fadvise: don't return -EINVAL when filesystem cannot implement fadvise()
Patches currently in -mm which might be from kosaki.motohiro@xxxxxxxxxxxxxx are
linux-next.patch
memory-hotplug-fix-invalid-memory-access-caused-by-stale-kswapd-pointer.patch
memory-hotplug-fix-invalid-memory-access-caused-by-stale-kswapd-pointer-fix.patch
c-r-prctl-less-paranoid-prctl_set_mm_exe_file.patch
hugetlb-rename-max_hstate-to-hugetlb_max_hstate.patch
hugetlb-dont-use-err_ptr-with-vm_fault-values.patch
hugetlb-add-an-inline-helper-for-finding-hstate-index.patch
hugetlb-use-mmu_gather-instead-of-a-temporary-linked-list-for-accumulating-pages.patch
hugetlb-avoid-taking-i_mmap_mutex-in-unmap_single_vma-for-hugetlb.patch
hugetlb-simplify-migrate_huge_page.patch
hugetlb-add-a-list-for-tracking-in-use-hugetlb-pages.patch
hugetlb-make-some-static-variables-global.patch
mm-hugetlb-add-new-hugetlb-cgroup.patch
hugetlb-cgroup-add-the-cgroup-pointer-to-page-lru.patch
hugetlb-cgroup-add-charge-uncharge-routines-for-hugetlb-cgroup.patch
hugetlb-cgroup-add-support-for-cgroup-removal.patch
hugetlb-cgroup-add-hugetlb-cgroup-control-files.patch
hugetlb-cgroup-migrate-hugetlb-cgroup-info-from-oldpage-to-new-page-during-migration.patch
hugetlb-cgroup-add-hugetlb-controller-documentation.patch
mm-oom-do-not-schedule-if-current-has-been-killed.patch
mm-fadvise-dont-return-einval-when-filesystem-cannot-implement-fadvise.patch
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