diff options
| author | Jens Axboe <axboe@kernel.dk> | 2024-12-20 08:47:50 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-01-25 20:22:44 -0800 |
| commit | d94d23fdd7529f1f3218235d1e0a69e9856907b7 (patch) | |
| tree | 4d141ebef762478f35f56094ba9ce7b2da852598 | |
| parent | 1d4457576570627e1702614bc060b55d95b85e39 (diff) | |
mm: add FGP_DONTCACHE folio creation flag
Callers can pass this in for uncached folio creation, in which case if a
folio is newly created it gets marked as uncached. If a folio exists for
this index and lookup succeeds, then it will not get marked as uncached.
If an !uncached lookup finds a cached folio, clear the flag. For that
case, there are competeting uncached and cached users of the folio, and it
should not get pruned.
Link: https://lkml.kernel.org/r/20241220154831.1086649-13-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Chris Mason <clm@meta.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/pagemap.h | 2 | ||||
| -rw-r--r-- | mm/filemap.c | 5 |
2 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index d53c49abead6..47bfc6b1b632 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -710,6 +710,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping, * * %FGP_NOFS - __GFP_FS will get cleared in gfp. * * %FGP_NOWAIT - Don't block on the folio lock. * * %FGP_STABLE - Wait for the folio to be stable (finished writeback) + * * %FGP_DONTCACHE - Uncached buffered IO * * %FGP_WRITEBEGIN - The flags to use in a filesystem write_begin() * implementation. */ @@ -723,6 +724,7 @@ typedef unsigned int __bitwise fgf_t; #define FGP_NOWAIT ((__force fgf_t)0x00000020) #define FGP_FOR_MMAP ((__force fgf_t)0x00000040) #define FGP_STABLE ((__force fgf_t)0x00000080) +#define FGP_DONTCACHE ((__force fgf_t)0x00000100) #define FGF_GET_ORDER(fgf) (((__force unsigned)fgf) >> 26) /* top 6 bits */ #define FGP_WRITEBEGIN (FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE) diff --git a/mm/filemap.c b/mm/filemap.c index 0aa3861aed45..279959cf9300 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1973,6 +1973,8 @@ no_page: /* Init accessed so avoid atomic mark_page_accessed later */ if (fgp_flags & FGP_ACCESSED) __folio_set_referenced(folio); + if (fgp_flags & FGP_DONTCACHE) + __folio_set_dropbehind(folio); err = filemap_add_folio(mapping, folio, index, gfp); if (!err) @@ -1995,6 +1997,9 @@ no_page: if (!folio) return ERR_PTR(-ENOENT); + /* not an uncached lookup, clear uncached if set */ + if (folio_test_dropbehind(folio) && !(fgp_flags & FGP_DONTCACHE)) + folio_clear_dropbehind(folio); return folio; } EXPORT_SYMBOL(__filemap_get_folio); |