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| author | Christoph Hellwig <hch@lst.de> | 2024-02-19 07:27:15 +0100 |
|---|---|---|
| committer | Chandan Babu R <chandanbabu@kernel.org> | 2024-02-21 11:36:51 +0530 |
| commit | 9d8b36744935f83c5553e6f242b9961f676628ed (patch) | |
| tree | 4bae63bbc52de61910b77e6f891965bab73409dc /mm/shmem.c | |
| parent | be9d93661d548a41bb8f135b9953191f0fb2e44b (diff) | |
| download | linux-stable-9d8b36744935f83c5553e6f242b9961f676628ed.tar.gz linux-stable-9d8b36744935f83c5553e6f242b9961f676628ed.tar.bz2 linux-stable-9d8b36744935f83c5553e6f242b9961f676628ed.zip | |
shmem: document how to "persist" data when using shmem_*file_setup
Add a blurb that simply dirtying the folio will persist data for in-kernel
shmem files. This is what most of the callers already do.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 95e70e9ea060..fb76da93d369 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2147,6 +2147,10 @@ unlock: * Looks up the page cache entry at @inode & @index. If a folio is * present, it is returned locked with an increased refcount. * + * If the caller modifies data in the folio, it must call folio_mark_dirty() + * before unlocking the folio to ensure that the folio is not reclaimed. + * There is no need to reserve space before calling folio_mark_dirty(). + * * When no folio is found, the behavior depends on @sgp: * - for SGP_READ, *foliop is %NULL and 0 is returned * - for SGP_NOALLOC, *foliop is %NULL and -ENOENT is returned |