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shmem: export shmem_get_folio

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Export shmem_get_folio as a slightly lower-level variant of
shmem_read_folio_gfp.  This will be useful for XFS xfile use cases
that want to pass SGP_NOALLOC or get a locked page, which the thin
shmem_read_folio_gfp wrapper can't provide.

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>
This commit is contained in:
Christoph Hellwig 2024-02-19 07:27:13 +01:00 committed by Chandan Babu R
parent 1cd81faaf6
commit d7468609ee
1 changed files with 20 additions and 0 deletions
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mm/shmem.c
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@ -2137,12 +2137,32 @@ unlock:
return error; return error;
} }
/**
* shmem_get_folio - find, and lock a shmem folio.
* @inode: inode to search
* @index: the page index.
* @foliop: pointer to the folio if found
* @sgp: SGP_* flags to control behavior
*
* Looks up the page cache entry at @inode & @index. If a folio is
* present, it is returned locked with an increased refcount.
*
* 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
* - for all other flags a new folio is allocated, inserted into the
* page cache and returned locked in @foliop.
*
* Context: May sleep.
* Return: 0 if successful, else a negative error code.
*/
int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop, int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
enum sgp_type sgp) enum sgp_type sgp)
{ {
return shmem_get_folio_gfp(inode, index, foliop, sgp, return shmem_get_folio_gfp(inode, index, foliop, sgp,
mapping_gfp_mask(inode->i_mapping), NULL, NULL); mapping_gfp_mask(inode->i_mapping), NULL, NULL);
} }
EXPORT_SYMBOL_GPL(shmem_get_folio);
/* /*
* This is like autoremove_wake_function, but it removes the wait queue * This is like autoremove_wake_function, but it removes the wait queue