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fuse: remove fuse_readpages_end() null mapping check

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Remove extra logic in fuse_readpages_end() that checks against null
folio mappings. This was added in commit ce534fb052 ("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 ef6a3c6311 ("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@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Joanne Koong 2025-08-29 16:56:27 -07:00 committed by Miklos Szeredi
parent b3c7ab1d25
commit 02d47e213d
1 changed files with 11 additions and 13 deletions
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24
fs/fuse/file.c
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@ -865,22 +865,20 @@ 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;
struct address_space *mapping;
struct inode *inode;
for (i = 0; mapping == NULL && i < ap->num_folios; i++)
mapping = ap->folios[i]->mapping;
WARN_ON_ONCE(!ap->num_folios);
mapping = ap->folios[0]->mapping;
inode = mapping->host;
if (mapping) {
struct inode *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++) {
folio_end_read(ap->folios[i], !err);