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authorDavid Howells <dhowells@redhat.com>2023-06-28 11:48:51 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-08-18 10:12:12 -0700
commit0201ebf274a306a6ebb95e5dc2d6a0a27c737cac (patch)
treef419d3eba3454f01be5f2be92697d796af49bccd /mm/truncate.c
parentdba438bd7663fefab870a6dd4b01ed0923c32d79 (diff)
mm: merge folio_has_private()/filemap_release_folio() call pairs
Patch series "mm, netfs, fscache: Stop read optimisation when folio removed from pagecache", v7. This fixes an optimisation in fscache whereby we don't read from the cache for a particular file until we know that there's data there that we don't have in the pagecache. The problem is that I'm no longer using PG_fscache (aka PG_private_2) to indicate that the page is cached and so I don't get a notification when a cached page is dropped from the pagecache. The first patch merges some folio_has_private() and filemap_release_folio() pairs and introduces a helper, folio_needs_release(), to indicate if a release is required. The second patch is the actual fix. Following Willy's suggestions[1], it adds an AS_RELEASE_ALWAYS flag to an address_space that will make filemap_release_folio() always call ->release_folio(), even if PG_private/PG_private_2 aren't set. folio_needs_release() is altered to add a check for this. This patch (of 2): Make filemap_release_folio() check folio_has_private(). Then, in most cases, where a call to folio_has_private() is immediately followed by a call to filemap_release_folio(), we can get rid of the test in the pair. There are a couple of sites in mm/vscan.c that this can't so easily be done. In shrink_folio_list(), there are actually three cases (something different is done for incompletely invalidated buffers), but filemap_release_folio() elides two of them. In shrink_active_list(), we don't have have the folio lock yet, so the check allows us to avoid locking the page unnecessarily. A wrapper function to check if a folio needs release is provided for those places that still need to do it in the mm/ directory. This will acquire additional parts to the condition in a future patch. After this, the only remaining caller of folio_has_private() outside of mm/ is a check in fuse. Link: https://lkml.kernel.org/r/20230628104852.3391651-1-dhowells@redhat.com Link: https://lkml.kernel.org/r/20230628104852.3391651-2-dhowells@redhat.com Reported-by: Rohith Surabattula <rohiths.msft@gmail.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: David Howells <dhowells@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Steve French <sfrench@samba.org> Cc: Shyam Prasad N <nspmangalore@gmail.com> Cc: Rohith Surabattula <rohiths.msft@gmail.com> Cc: Dave Wysochanski <dwysocha@redhat.com> Cc: Dominique Martinet <asmadeus@codewreck.org> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Xiubo Li <xiubli@redhat.com> Cc: Jingbo Xu <jefflexu@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/truncate.c')
-rw-r--r--mm/truncate.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index 2f28cc0e12ef..bd4fafd67f95 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -19,7 +19,6 @@
#include <linux/highmem.h>
#include <linux/pagevec.h>
#include <linux/task_io_accounting_ops.h>
-#include <linux/buffer_head.h> /* grr. try_to_release_page */
#include <linux/shmem_fs.h>
#include <linux/rmap.h>
#include "internal.h"
@@ -276,7 +275,7 @@ static long mapping_evict_folio(struct address_space *mapping,
if (folio_ref_count(folio) >
folio_nr_pages(folio) + folio_has_private(folio) + 1)
return 0;
- if (folio_has_private(folio) && !filemap_release_folio(folio, 0))
+ if (!filemap_release_folio(folio, 0))
return 0;
return remove_mapping(mapping, folio);
@@ -573,8 +572,7 @@ static int invalidate_complete_folio2(struct address_space *mapping,
if (folio->mapping != mapping)
return 0;
- if (folio_has_private(folio) &&
- !filemap_release_folio(folio, GFP_KERNEL))
+ if (!filemap_release_folio(folio, GFP_KERNEL))
return 0;
spin_lock(&mapping->host->i_lock);