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mm: factor out the order calculation into a new helper

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Patch series "Support large folios for tmpfs", v3.

Traditionally, tmpfs only supported PMD-sized large folios.  However
nowadays with other file systems supporting any sized large folios, and
extending anonymous to support mTHP, we should not restrict tmpfs to
allocating only PMD-sized large folios, making it more special.  Instead,
we should allow tmpfs can allocate any sized large folios.

Considering that tmpfs already has the 'huge=' option to control the
PMD-sized large folios allocation, we can extend the 'huge=' option to
allow any sized large folios.  The semantics of the 'huge=' mount option
are:

huge=never: no any sized large folios
huge=always: any sized large folios
huge=within_size: like 'always' but respect the i_size
huge=advise: like 'always' if requested with madvise()

Note: for tmpfs mmap() faults, due to the lack of a write size hint, still
allocate the PMD-sized large folios if huge=always/within_size/advise is
set.

Moreover, the 'deny' and 'force' testing options controlled by
'/sys/kernel/mm/transparent_hugepage/shmem_enabled', still retain the same
semantics.  The 'deny' can disable any sized large folios for tmpfs, while
the 'force' can enable PMD sized large folios for tmpfs.


This patch (of 6):

Factor out the order calculation into a new helper, which can be reused by
shmem in the following patch.

Link: https://lkml.kernel.org/r/cover.1732779148.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/5505f9ea50942820c1924d1803bfdd3a524e54f6.1732779148.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baolin Wang 2024-11-28 15:40:39 +08:00 committed by Andrew Morton
parent d40797d672
commit da243c5479
1 changed files with 13 additions and 3 deletions
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16
include/linux/pagemap.h
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@ -727,6 +727,16 @@ typedef unsigned int __bitwise fgf_t;
#define FGP_WRITEBEGIN (FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)
static inline unsigned int filemap_get_order(size_t size)
{
unsigned int shift = ilog2(size);
if (shift <= PAGE_SHIFT)
return 0;
return shift - PAGE_SHIFT;
}
/**
* fgf_set_order - Encode a length in the fgf_t flags.
* @size: The suggested size of the folio to create.
@ -740,11 +750,11 @@ typedef unsigned int __bitwise fgf_t;
*/
static inline fgf_t fgf_set_order(size_t size)
{
unsigned int shift = ilog2(size);
unsigned int order = filemap_get_order(size);
if (shift <= PAGE_SHIFT)
if (!order)
return 0;
return (__force fgf_t)((shift - PAGE_SHIFT) << 26);
return (__force fgf_t)(order << 26);
}
void *filemap_get_entry(struct address_space *mapping, pgoff_t index);