From b27652d935f41793c5e229a1e8b3a8bb3afe3cc1 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 24 Dec 2020 12:55:56 -0500 Subject: [PATCH] mm/filemap: Add FGP_STABLE Allow filemap_get_folio() to wait for writeback to complete (if the filesystem wants that behaviour). This is the folio equivalent of grab_cache_page_write_begin(), which is moved into the folio-compat file as a reminder to migrate all the code using it. This paves the way for getting rid of AOP_FLAG_NOFS once grab_cache_page_write_begin() is removed. Kernel grows by 11 bytes. filemap_get_folio() grows by 33 bytes but grab_cache_page_write_begin() shrinks by 22 bytes to make up for it. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: David Howells Acked-by: Vlastimil Babka --- include/linux/pagemap.h | 1 + mm/filemap.c | 25 +++---------------------- mm/folio-compat.c | 13 +++++++++++++ 3 files changed, 17 insertions(+), 22 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 401a90336a2c..b68b053e581f 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -301,6 +301,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping, #define FGP_FOR_MMAP 0x00000040 #define FGP_HEAD 0x00000080 #define FGP_ENTRY 0x00000100 +#define FGP_STABLE 0x00000200 struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, int fgp_flags, gfp_t gfp); diff --git a/mm/filemap.c b/mm/filemap.c index de4cc1b9aa9b..3e9feb5cc570 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1872,6 +1872,7 @@ out: * * %FGP_WRITE - The page will be written to by the caller. * * %FGP_NOFS - __GFP_FS will get cleared in gfp. * * %FGP_NOWAIT - Don't get blocked by page lock. + * * %FGP_STABLE - Wait for the folio to be stable (finished writeback) * * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even * if the %GFP flags specified for %FGP_CREAT are atomic. @@ -1922,6 +1923,8 @@ repeat: folio_clear_idle(folio); } + if (fgp_flags & FGP_STABLE) + folio_wait_stable(folio); no_page: if (!folio && (fgp_flags & FGP_CREAT)) { int err; @@ -3704,28 +3707,6 @@ out: } EXPORT_SYMBOL(generic_file_direct_write); -/* - * Find or create a page at the given pagecache position. Return the locked - * page. This function is specifically for buffered writes. - */ -struct page *grab_cache_page_write_begin(struct address_space *mapping, - pgoff_t index, unsigned flags) -{ - struct page *page; - int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT; - - if (flags & AOP_FLAG_NOFS) - fgp_flags |= FGP_NOFS; - - page = pagecache_get_page(mapping, index, fgp_flags, - mapping_gfp_mask(mapping)); - if (page) - wait_for_stable_page(page); - - return page; -} -EXPORT_SYMBOL(grab_cache_page_write_begin); - ssize_t generic_perform_write(struct file *file, struct iov_iter *i, loff_t pos) { diff --git a/mm/folio-compat.c b/mm/folio-compat.c index e833e680e944..5b6ae1da314e 100644 --- a/mm/folio-compat.c +++ b/mm/folio-compat.c @@ -116,6 +116,7 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping, } EXPORT_SYMBOL(add_to_page_cache_lru); +noinline struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, int fgp_flags, gfp_t gfp) { @@ -127,3 +128,15 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, return folio_file_page(folio, index); } EXPORT_SYMBOL(pagecache_get_page); + +struct page *grab_cache_page_write_begin(struct address_space *mapping, + pgoff_t index, unsigned flags) +{ + unsigned fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE; + + if (flags & AOP_FLAG_NOFS) + fgp_flags |= FGP_NOFS; + return pagecache_get_page(mapping, index, fgp_flags, + mapping_gfp_mask(mapping)); +} +EXPORT_SYMBOL(grab_cache_page_write_begin);