tmpfs: add shmem_read_mapping_page_gfp
authorHugh Dickins <hughd@google.com>
Mon, 27 Jun 2011 23:18:04 +0000 (16:18 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 28 Jun 2011 01:00:12 +0000 (18:00 -0700)
commitd9d90e5eb70e09903dadff42099b6c948f814050
treec3ab73df6dee61f9403bfd819a6b0cb9f3ca6085
parent94c1e62df4494b79782cb9c7279f827212d1de70
tmpfs: add shmem_read_mapping_page_gfp

Although it is used (by i915) on nothing but tmpfs, read_cache_page_gfp()
is unsuited to tmpfs, because it inserts a page into pagecache before
calling the filesystem's ->readpage: tmpfs may have pages in swapcache
which only it knows how to locate and switch to filecache.

At present tmpfs provides a ->readpage method, and copes with this by
copying pages; but soon we can simplify it by removing its ->readpage.
Provide shmem_read_mapping_page_gfp() now, ready for that transition,

Export shmem_read_mapping_page_gfp() and add it to list in shmem_fs.h,
with shmem_read_mapping_page() inline for the common mapping_gfp case.

(shmem_read_mapping_page_gfp or shmem_read_cache_page_gfp? Generally the
read_mapping_page functions use the mapping's ->readpage, and the
read_cache_page functions use the supplied filler, so I think
read_cache_page_gfp was slightly misnamed.)

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/shmem_fs.h
mm/shmem.c