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authorChristoph Hellwig <hch@lst.de>2023-03-07 17:34:10 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-04-06 05:42:42 +0300
commit66dabbb65d673aef40dd17bf62c042be8f6d4a4b (patch)
treea14c48222ab659cc6a9344ca6a1468a09c09eb42 /mm/filemap.c
parent48c9d11375fc66f1e59d0e9b27d121e015a50904 (diff)
downloadlinux-66dabbb65d673aef40dd17bf62c042be8f6d4a4b.tar.xz
mm: return an ERR_PTR from __filemap_get_folio
Instead of returning NULL for all errors, distinguish between: - no entry found and not asked to allocated (-ENOENT) - failed to allocate memory (-ENOMEM) - would block (-EAGAIN) so that callers don't have to guess the error based on the passed in flags. Also pass through the error through the direct callers: filemap_get_folio, filemap_lock_folio filemap_grab_folio and filemap_get_incore_folio. [hch@lst.de: fix null-pointer deref] Link: https://lkml.kernel.org/r/20230310070023.GA13563@lst.de Link: https://lkml.kernel.org/r/20230310043137.GA1624890@u2004 Link: https://lkml.kernel.org/r/20230307143410.28031-8-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> [nilfs2] Cc: Andreas Gruenbacher <agruenba@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index ac161b50f5bc..a34abfe8c654 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1907,7 +1907,7 @@ out:
*
* If there is a page cache page, it is returned with an increased refcount.
*
- * Return: The found folio or %NULL otherwise.
+ * Return: The found folio or an ERR_PTR() otherwise.
*/
struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
int fgp_flags, gfp_t gfp)
@@ -1925,7 +1925,7 @@ repeat:
if (fgp_flags & FGP_NOWAIT) {
if (!folio_trylock(folio)) {
folio_put(folio);
- return NULL;
+ return ERR_PTR(-EAGAIN);
}
} else {
folio_lock(folio);
@@ -1964,7 +1964,7 @@ no_page:
folio = filemap_alloc_folio(gfp, 0);
if (!folio)
- return NULL;
+ return ERR_PTR(-ENOMEM);
if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
fgp_flags |= FGP_LOCK;
@@ -1989,6 +1989,8 @@ no_page:
folio_unlock(folio);
}
+ if (!folio)
+ return ERR_PTR(-ENOENT);
return folio;
}
EXPORT_SYMBOL(__filemap_get_folio);
@@ -3258,7 +3260,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
* Do we have something in the page cache already?
*/
folio = filemap_get_folio(mapping, index);
- if (likely(folio)) {
+ if (likely(!IS_ERR(folio))) {
/*
* We found the page, so try async readahead before waiting for
* the lock.
@@ -3287,7 +3289,7 @@ retry_find:
folio = __filemap_get_folio(mapping, index,
FGP_CREAT|FGP_FOR_MMAP,
vmf->gfp_mask);
- if (!folio) {
+ if (IS_ERR(folio)) {
if (fpin)
goto out_retry;
filemap_invalidate_unlock_shared(mapping);
@@ -3638,7 +3640,7 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
filler = mapping->a_ops->read_folio;
repeat:
folio = filemap_get_folio(mapping, index);
- if (!folio) {
+ if (IS_ERR(folio)) {
folio = filemap_alloc_folio(gfp, 0);
if (!folio)
return ERR_PTR(-ENOMEM);