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fs/cachefiles: Remove wait_bit_key layout dependency

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commit 39f985c8f667c80a3d1eb19d31138032fa36b09e upstream.

Cachefiles was relying on wait_page_key and wait_bit_key being the
same layout, which is fragile.  Now that wait_page_key is exposed in
the pagemap.h header, we can remove that fragility

A comment on the need to maintain structure layout equivalence was added by
Linus[1] and that is no longer applicable.

Fixes: 6290602709 ("mm: add PageWaiters indicating tasks are waiting for a page bit")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: kafs-testing@auristor.com
cc: linux-cachefs@redhat.com
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20210320054104.1300774-2-willy@infradead.org/
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3510ca20ece0150af6b10c77a74ff1b5c198e3e2 [1]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-03-20 05:40:38 +00:00 committed by Greg Kroah-Hartman
parent 002ea848d7
commit 6f15c02ebb
2 changed files with 3 additions and 5 deletions
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7
fs/cachefiles/rdwr.c
View File

@ -24,17 +24,16 @@ static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode,
container_of(wait, struct cachefiles_one_read, monitor);
struct cachefiles_object *object;
struct fscache_retrieval *op = monitor->op;
struct wait_bit_key *key = _key;
struct wait_page_key *key = _key;
struct page *page = wait->private;
ASSERT(key);
_enter("{%lu},%u,%d,{%p,%u}",
monitor->netfs_page->index, mode, sync,
key->flags, key->bit_nr);
key->page, key->bit_nr);
if (key->flags != &page->flags ||
key->bit_nr != PG_locked)
if (key->page != page || key->bit_nr != PG_locked)
return 0;
_debug("--- monitor %p %lx ---", page, page->flags);

1
include/linux/pagemap.h
View File

@ -559,7 +559,6 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
return pgoff;
}
/* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */
struct wait_page_key {
struct page *page;
int bit_nr;