Commit 6abbaa5b authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

fs/netfs: Add folio fscache functions 



Match the page writeback functions by adding
folio_start_fscache(), folio_end_fscache(), folio_wait_fscache() and
folio_wait_fscache_killable().  Remove set_page_private_2().  Also rewrite
the kernel-doc to describe when to use the function rather than what the
function does, and include the kernel-doc in the appropriate rst file.
Saves 31 bytes of text in netfs_rreq_unlock() due to set_page_fscache()
calling page_folio() once instead of three times.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
parent b47393f8

Documentation/filesystems/netfs_library.rst

+2 −0
Original line number Diff line number Diff line
@@ -524,3 +524,5 @@ Note that these methods are passed a pointer to the cache resource structure, 
not the read request structure as they could be used in other situations where

there isn't a read request structure as well, such as writing dirty data to the

cache.



.. kernel-doc:: include/linux/netfs.h

include/linux/netfs.h

+48 −27
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
 * Overload PG_private_2 to give us PG_fscache - this is used to indicate that

 * a page is currently backed by a local disk cache

 */

#define folio_test_fscache(folio)	folio_test_private_2(folio)

#define PageFsCache(page)		PagePrivate2((page))

#define SetPageFsCache(page)		SetPagePrivate2((page))

#define ClearPageFsCache(page)		ClearPagePrivate2((page))
@@ -29,57 +30,77 @@ 
#define TestClearPageFsCache(page)	TestClearPagePrivate2((page))



/**

 * set_page_fscache - Set PG_fscache on a page and take a ref

 * @page: The page.

 * folio_start_fscache - Start an fscache write on a folio.

 * @folio: The folio.

 *

 * Set the PG_fscache (PG_private_2) flag on a page and take the reference

 * needed for the VM to handle its lifetime correctly.  This sets the flag and

 * takes the reference unconditionally, so care must be taken not to set the

 * flag again if it's already set.

 * Call this function before writing a folio to a local cache.  Starting a

 * second write before the first one finishes is not allowed.

 */

static inline void set_page_fscache(struct page *page)

static inline void folio_start_fscache(struct folio *folio)

{

	set_page_private_2(page);

	VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);

	folio_get(folio);

	folio_set_private_2(folio);

}



/**

 * end_page_fscache - Clear PG_fscache and release any waiters

 * @page: The page

 *

 * Clear the PG_fscache (PG_private_2) bit on a page and wake up any sleepers

 * waiting for this.  The page ref held for PG_private_2 being set is released.

 * folio_end_fscache - End an fscache write on a folio.

 * @folio: The folio.

 *

 * This is, for example, used when a netfs page is being written to a local

 * disk cache, thereby allowing writes to the cache for the same page to be

 * serialised.

 * Call this function after the folio has been written to the local cache.

 * This will wake any sleepers waiting on this folio.

 */

static inline void end_page_fscache(struct page *page)

static inline void folio_end_fscache(struct folio *folio)

{

	folio_end_private_2(page_folio(page));

	folio_end_private_2(folio);

}



/**

 * wait_on_page_fscache - Wait for PG_fscache to be cleared on a page

 * @page: The page to wait on

 * folio_wait_fscache - Wait for an fscache write on this folio to end.

 * @folio: The folio.

 *

 * Wait for PG_fscache (aka PG_private_2) to be cleared on a page.

 * If this folio is currently being written to a local cache, wait for

 * the write to finish.  Another write may start after this one finishes,

 * unless the caller holds the folio lock.

 */

static inline void wait_on_page_fscache(struct page *page)

static inline void folio_wait_fscache(struct folio *folio)

{

	folio_wait_private_2(page_folio(page));

	folio_wait_private_2(folio);

}



/**

 * wait_on_page_fscache_killable - Wait for PG_fscache to be cleared on a page

 * @page: The page to wait on

 * folio_wait_fscache_killable - Wait for an fscache write on this folio to end.

 * @folio: The folio.

 *

 * Wait for PG_fscache (aka PG_private_2) to be cleared on a page or until a

 * fatal signal is received by the calling task.

 * If this folio is currently being written to a local cache, wait

 * for the write to finish or for a fatal signal to be received.

 * Another write may start after this one finishes, unless the caller

 * holds the folio lock.

 *

 * Return:

 * - 0 if successful.

 * - -EINTR if a fatal signal was encountered.

 */

static inline int folio_wait_fscache_killable(struct folio *folio)

{

	return folio_wait_private_2_killable(folio);

}



static inline void set_page_fscache(struct page *page)

{

	folio_start_fscache(page_folio(page));

}



static inline void end_page_fscache(struct page *page)

{

	folio_end_private_2(page_folio(page));

}



static inline void wait_on_page_fscache(struct page *page)

{

	folio_wait_private_2(page_folio(page));

}



static inline int wait_on_page_fscache_killable(struct page *page)

{

	return folio_wait_private_2_killable(page_folio(page));

include/linux/pagemap.h

+0 −16
Original line number Diff line number Diff line
@@ -779,22 +779,6 @@ int __set_page_dirty_no_writeback(struct page *page); 


void page_endio(struct page *page, bool is_write, int err);



/**

 * set_page_private_2 - Set PG_private_2 on a page and take a ref

 * @page: The page.

 *

 * Set the PG_private_2 flag on a page and take the reference needed for the VM

 * to handle its lifetime correctly.  This sets the flag and takes the

 * reference unconditionally, so care must be taken not to set the flag again

 * if it's already set.

 */

static inline void set_page_private_2(struct page *page)

{

	page = compound_head(page);

	get_page(page);

	SetPagePrivate2(page);

}



void folio_end_private_2(struct folio *folio);

void folio_wait_private_2(struct folio *folio);

int folio_wait_private_2_killable(struct folio *folio);