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mm: add FGP_ENTRY 

The functionality of find_lock_entry() and find_get_entry() can be
provided by pagecache_get_page(), which lets us delete find_lock_entry()
and make find_get_entry() static.

Link: https://lkml.kernel.org/r/20201112212641.27837-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-02-25 17:15:36 -08:00 committed by Linus Torvalds
parent 8c647dd1e3
commit 44835d20b2
5 changed files with 13 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/pagemap.h
View File

@ -315,6 +315,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
#define FGP_NOWAIT 0x00000020
#define FGP_FOR_MMAP 0x00000040
#define FGP_HEAD 0x00000080
#define FGP_ENTRY 0x00000100
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
int fgp_flags, gfp_t cache_gfp_mask);

44
mm/filemap.c
View File

@ -1658,7 +1658,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
}
EXPORT_SYMBOL(page_cache_prev_miss);
/**
/*
* find_get_entry - find and get a page cache entry
* @mapping: the address_space to search
* @index: The page cache index.
@ -1671,7 +1671,7 @@ EXPORT_SYMBOL(page_cache_prev_miss);
*
* Return: The head page or shadow entry, %NULL if nothing is found.
*/
struct page *find_get_entry(struct address_space *mapping, pgoff_t index)
static struct page *find_get_entry(struct address_space *mapping, pgoff_t index)
{
XA_STATE(xas, &mapping->i_pages, index);
struct page *page;
@ -1707,39 +1707,6 @@ struct page *find_get_entry(struct address_space *mapping, pgoff_t index)
return page;
}
/**
* find_lock_entry - Locate and lock a page cache entry.
* @mapping: The address_space to search.
* @index: The page cache index.
*
* Looks up the page at @mapping & @index. If there is a page in the
* cache, the head page is returned locked and with an increased refcount.
*
* If the slot holds a shadow entry of a previously evicted page, or a
* swap entry from shmem/tmpfs, it is returned.
*
* Context: May sleep.
* Return: The head page or shadow entry, %NULL if nothing is found.
*/
struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
{
struct page *page;
repeat:
page = find_get_entry(mapping, index);
if (page && !xa_is_value(page)) {
lock_page(page);
/* Has the page been truncated? */
if (unlikely(page->mapping != mapping)) {
unlock_page(page);
put_page(page);
goto repeat;
}
VM_BUG_ON_PAGE(!thp_contains(page, index), page);
}
return page;
}
/**
* pagecache_get_page - Find and get a reference to a page.
* @mapping: The address_space to search.
@ -1755,6 +1722,8 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
* * %FGP_LOCK - The page is returned locked.
* * %FGP_HEAD - If the page is present and a THP, return the head page
* rather than the exact page specified by the index.
* * %FGP_ENTRY - If there is a shadow / swap / DAX entry, return it
* instead of allocating a new page to replace it.
* * %FGP_CREAT - If no page is present then a new page is allocated using
* @gfp_mask and added to the page cache and the VM's LRU list.
* The page is returned locked and with an increased refcount.
@ -1779,8 +1748,11 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
repeat:
page = find_get_entry(mapping, index);
if (xa_is_value(page))
if (xa_is_value(page)) {
if (fgp_flags & FGP_ENTRY)
return page;
page = NULL;
}
if (!page)
goto no_page;

3
mm/internal.h
View File

@ -60,9 +60,6 @@ static inline void force_page_cache_readahead(struct address_space *mapping,
force_page_cache_ra(&ractl, &file->f_ra, nr_to_read);
}
struct page *find_get_entry(struct address_space *mapping, pgoff_t index);
struct page *find_lock_entry(struct address_space *mapping, pgoff_t index);
/**
* page_evictable - test whether a page is evictable
* @page: the page to test

3
mm/shmem.c
View File

@ -1812,7 +1812,8 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
sbinfo = SHMEM_SB(inode->i_sb);
charge_mm = vma ? vma->vm_mm : current->mm;
page = find_lock_entry(mapping, index);
page = pagecache_get_page(mapping, index,
FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0);
if (xa_is_value(page)) {
error = shmem_swapin_page(inode, index, &page,
sgp, gfp, vma, fault_type);

3
mm/swap_state.c
View File

@ -403,7 +403,8 @@ struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
{
swp_entry_t swp;
struct swap_info_struct *si;
struct page *page = find_get_entry(mapping, index);
struct page *page = pagecache_get_page(mapping, index,
FGP_ENTRY | FGP_HEAD, 0);
if (!page)
return page;