[PATCH v2 4/7] filemap: Add fgp_t typedef

Matthew Wilcox (Oracle)
2023-06-02T22:24:58Z

Similarly to gfp_t, define fgp_t as its own type to prevent various
misuses and confusion. Move the documentation to the definition of the
type insted of burying it in the __filemap_get_folio() documentation.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/btrfs/file.c | 6 +++---
fs/f2fs/compress.c | 2 +-
fs/f2fs/f2fs.h | 2 +-
fs/iomap/buffered-io.c | 2 +-
include/linux/pagemap.h | 48 +++++++++++++++++++++++++++++++----------
mm/filemap.c | 19 ++--------------
mm/folio-compat.c | 2 +-
7 files changed, 46 insertions(+), 35 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f649647392e0..4bbbbdafb472 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -876,9 +876,9 @@ static int prepare_uptodate_page(struct inode *inode,
return 0;
}

-static unsigned int get_prepare_fgp_flags(bool nowait)
+static fgp_t get_prepare_fgp_flags(bool nowait)
{
- unsigned int fgp_flags = FGP_LOCK | FGP_ACCESSED | FGP_CREAT;
+ fgp_t fgp_flags = FGP_LOCK | FGP_ACCESSED | FGP_CREAT;

if (nowait)
fgp_flags |= FGP_NOWAIT;
@@ -910,7 +910,7 @@ static noinline int prepare_pages(struct inode *inode, struct page **pages,
int i;
unsigned long index = pos >> PAGE_SHIFT;
gfp_t mask = get_prepare_gfp_flags(inode, nowait);
- unsigned int fgp_flags = get_prepare_fgp_flags(nowait);
+ fgp_t fgp_flags = get_prepare_fgp_flags(nowait);
int err = 0;
int faili;

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 11653fa79289..ee358f5f2a86 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1019,7 +1019,7 @@ static int prepare_compress_overwrite(struct compress_ctx *cc,
struct address_space *mapping = cc->inode->i_mapping;
struct page *page;
sector_t last_block_in_bio;
- unsigned fgp_flag = FGP_LOCK | FGP_WRITE | FGP_CREAT;
+ fgp_t fgp_flag = FGP_LOCK | FGP_WRITE | FGP_CREAT;
pgoff_t start_idx = start_idx_of_cluster(cc);
int i, ret;

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d211ee89c158..a03c3df75f7c 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2715,7 +2715,7 @@ static inline struct page *f2fs_grab_cache_page(struct address_space *mapping,

static inline struct page *f2fs_pagecache_get_page(
struct address_space *mapping, pgoff_t index,
- int fgp_flags, gfp_t gfp_mask)
+ fgp_t fgp_flags, gfp_t gfp_mask)
{
if (time_to_inject(F2FS_M_SB(mapping), FAULT_PAGE_GET))
return NULL;
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 2054b85c9d9b..30d53b50ee0f 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -467,7 +467,7 @@ EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
*/
struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos)
{
- unsigned fgp = FGP_WRITEBEGIN | FGP_NOFS;
+ fgp_t fgp = FGP_WRITEBEGIN | FGP_NOFS;

if (iter->flags & IOMAP_NOWAIT)
fgp |= FGP_NOWAIT;
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a56308a9d1a4..7ab57a2bb576 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -497,22 +497,48 @@ pgoff_t page_cache_next_miss(struct address_space *mapping,
pgoff_t page_cache_prev_miss(struct address_space *mapping,
pgoff_t index, unsigned long max_scan);

-#define FGP_ACCESSED 0x00000001
-#define FGP_LOCK 0x00000002
-#define FGP_CREAT 0x00000004
-#define FGP_WRITE 0x00000008
-#define FGP_NOFS 0x00000010
-#define FGP_NOWAIT 0x00000020
-#define FGP_FOR_MMAP 0x00000040
-#define FGP_STABLE 0x00000080
+/**
+ * typedef fgp_t - Flags for getting folios from the page cache.
+ *
+ * Most users of the page cache will not need to use these flags;
+ * there are convenience functions such as filemap_get_folio() and
+ * filemap_lock_folio(). For users which need more control over exactly
+ * what is done with the folios, these flags to __filemap_get_folio()
+ * are available.
+ *
+ * * %FGP_ACCESSED - The folio will be marked accessed.
+ * * %FGP_LOCK - The folio is returned locked.
+ * * %FGP_CREAT - If no folio is present then a new folio is allocated,
+ * added to the page cache and the VM's LRU list. The folio is
+ * returned locked.
+ * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
+ * folio is already in cache. If the folio was allocated, unlock it
+ * before returning so the caller can do the same dance.
+ * * %FGP_WRITE - The folio will be written to by the caller.
+ * * %FGP_NOFS - __GFP_FS will get cleared in gfp.
+ * * %FGP_NOWAIT - Don't block on the folio lock.
+ * * %FGP_STABLE - Wait for the folio to be stable (finished writeback)
+ * * %FGP_WRITEBEGIN - The flags to use in a filesystem write_begin()
+ * implementation.
+ */
+typedef unsigned int __bitwise fgp_t;
+
+#define FGP_ACCESSED ((__force fgp_t)0x00000001)
+#define FGP_LOCK ((__force fgp_t)0x00000002)
+#define FGP_CREAT ((__force fgp_t)0x00000004)
+#define FGP_WRITE ((__force fgp_t)0x00000008)
+#define FGP_NOFS ((__force fgp_t)0x00000010)
+#define FGP_NOWAIT ((__force fgp_t)0x00000020)
+#define FGP_FOR_MMAP ((__force fgp_t)0x00000040)
+#define FGP_STABLE ((__force fgp_t)0x00000080)

#define FGP_WRITEBEGIN (FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)

void *filemap_get_entry(struct address_space *mapping, pgoff_t index);
struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
- int fgp_flags, gfp_t gfp);
+ fgp_t fgp_flags, gfp_t gfp);
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
- int fgp_flags, gfp_t gfp);
+ fgp_t fgp_flags, gfp_t gfp);

/**
* filemap_get_folio - Find and get a folio.
@@ -586,7 +612,7 @@ static inline struct page *find_get_page(struct address_space *mapping,
}

static inline struct page *find_get_page_flags(struct address_space *mapping,
- pgoff_t offset, int fgp_flags)
+ pgoff_t offset, fgp_t fgp_flags)
{
return pagecache_get_page(mapping, offset, fgp_flags, 0);
}
diff --git a/mm/filemap.c b/mm/filemap.c
index b4c9bd368b7e..eb89a815f2f8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1887,30 +1887,15 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
*
* Looks up the page cache entry at @mapping & @index.
*
- * @fgp_flags can be zero or more of these flags:
- *
- * * %FGP_ACCESSED - The folio will be marked accessed.
- * * %FGP_LOCK - The folio is returned locked.
- * * %FGP_CREAT - If no page is present then a new page is allocated using
- * @gfp and added to the page cache and the VM's LRU list.
- * The page is returned locked and with an increased refcount.
- * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
- * page is already in cache. If the page was allocated, unlock it before
- * returning so the caller can do the same dance.
- * * %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.
*
- * If there is a page cache page, it is returned with an increased refcount.
+ * If this function returns a folio, it is returned with an increased refcount.
*
* Return: The found folio or an ERR_PTR() otherwise.
*/
struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
- int fgp_flags, gfp_t gfp)
+ fgp_t fgp_flags, gfp_t gfp)
{
struct folio *folio;

diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index c6f056c20503..ae1a737d2533 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -92,7 +92,7 @@ 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)
+ fgp_t fgp_flags, gfp_t gfp)
{
struct folio *folio;

--
2.39.2