Remove extra logic in fuse_readpages_end() that checks against null
folio mappings. This was added in commit ce534fb05292 ("fuse: allow
splice to move pages"):
"Since the remove_from_page_cache() + add_to_page_cache_locked()
are non-atomic it is possible that the page cache is repopulated in
between the two and add_to_page_cache_locked() will fail. This
could be fixed by creating a new atomic replace_page_cache_page()
function.
fuse_readpages_end() needed to be reworked so it works even if
page->mapping is NULL for some or all pages which can happen if the
add_to_page_cache_locked() failed."
Commit ef6a3c63112e ("mm: add replace_page_cache_page() function") added
atomic page cache replacement, which means the check against null
mappings can be removed.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
fs/fuse/file.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1659603f4cb6..87078f40d446 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -981,22 +981,20 @@ static void fuse_readpages_end(struct fuse_mount *fm, struct fuse_args *args,
struct fuse_args_pages *ap = &ia->ap;
size_t count = ia->read.in.size;
size_t num_read = args->out_args[0].size;
- struct address_space *mapping = NULL;
-
- for (i = 0; mapping == NULL && i < ap->num_folios; i++)
- mapping = ap->folios[i]->mapping;
+ struct address_space *mapping;
+ struct inode *inode;
- if (mapping) {
- struct inode *inode = mapping->host;
+ WARN_ON_ONCE(!ap->num_folios);
+ mapping = ap->folios[0]->mapping;
+ inode = mapping->host;
- /*
- * Short read means EOF. If file size is larger, truncate it
- */
- if (!err && num_read < count)
- fuse_short_read(inode, ia->read.attr_ver, num_read, ap);
+ /*
+ * Short read means EOF. If file size is larger, truncate it
+ */
+ if (!err && num_read < count)
+ fuse_short_read(inode, ia->read.attr_ver, num_read, ap);
- fuse_invalidate_atime(inode);
- }
+ fuse_invalidate_atime(inode);
for (i = 0; i < ap->num_folios; i++) {
iomap_finish_folio_read(ap->folios[i], ap->descs[i].offset,
--
2.47.3
