lkml.org 
[lkml]   [2021]   [Mar]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.11 243/254] fs/cachefiles: Remove wait_bit_key layout dependency
    Date
    From: Matthew Wilcox (Oracle) <willy@infradead.org>

    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    Linus[1] and that is no longer applicable.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: 62906027091f ("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>
    ---
    fs/cachefiles/rdwr.c | 7 +++----
    include/linux/pagemap.h | 1 -
    2 files changed, 3 insertions(+), 5 deletions(-)

    --- a/fs/cachefiles/rdwr.c
    +++ b/fs/cachefiles/rdwr.c
    @@ -24,17 +24,16 @@ static int cachefiles_read_waiter(wait_q
    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);
    --- a/include/linux/pagemap.h
    +++ b/include/linux/pagemap.h
    @@ -559,7 +559,6 @@ static inline pgoff_t linear_page_index(
    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;

    \
     
     \ /
      Last update: 2021-03-29 11:10    [W:2.942 / U:0.460 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site