linux-kernel - [PATCH 09/16] huge tmpfs: decide stat.st_blksize by shmem_is

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Date:   Fri, 30 Jul 2021 00:51:00 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
cc:     Hugh Dickins <hughd@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Michal Hocko <mhocko@...e.com>,
        Rik van Riel <riel@...riel.com>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Alexey Gladkov <legion@...nel.org>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Matthew Auld <matthew.auld@...el.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 09/16] huge tmpfs: decide stat.st_blksize by
 shmem_is_huge()

4.18 commit 89fdcd262fd4 ("mm: shmem: make stat.st_blksize return huge
page size if THP is on") added is_huge_enabled() to decide st_blksize:
now that hugeness can be defined per file, that too needs to be replaced
by shmem_is_huge().

Unless they have been fcntl'ed F_HUGEPAGE, this does give a different
answer (No) for small files on a "huge=within_size" mount: but that can
be considered a minor bugfix.  And a different answer (No) for unfcntl'ed
files on a "huge=advise" mount: I'm reluctant to complicate it, just to
reproduce the same debatable answer as before.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---
 mm/shmem.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 67a4b7a4849b..f50f2ede71da 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -712,15 +712,6 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
-static inline bool is_huge_enabled(struct shmem_sb_info *sbinfo)
-{
-	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
-	    (shmem_huge == SHMEM_HUGE_FORCE || sbinfo->huge) &&
-	    shmem_huge != SHMEM_HUGE_DENY)
-		return true;
-	return false;
-}
-
 /*
  * Like add_to_page_cache_locked, but error if expected item has gone.
  */
@@ -1101,7 +1092,6 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
 {
 	struct inode *inode = path->dentry->d_inode;
 	struct shmem_inode_info *info = SHMEM_I(inode);
-	struct shmem_sb_info *sb_info = SHMEM_SB(inode->i_sb);
 
 	if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
 		spin_lock_irq(&info->lock);
@@ -1110,7 +1100,7 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
 	}
 	generic_fillattr(&init_user_ns, inode, stat);
 
-	if (is_huge_enabled(sb_info))
+	if (shmem_is_huge(NULL, inode, 0))
 		stat->blksize = HPAGE_PMD_SIZE;
 
 	return 0;
-- 
2.26.2