fs: Add FGP_WRITEBEGIN

This particular combination of flags is used by most filesystems
in their ->write_begin method, although it does find use in a
few other places.  Before folios, it warranted its own function
(grab_cache_page_write_begin()), but I think that just having specialised
flags is enough.  It certainly helps the few places that have been
converted from grab_cache_page_write_begin() to __filemap_get_folio().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-2-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 2 insertions, 10 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 893625eacab9..2474cbc30712 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -306,15 +306,6 @@ static bool nfs_want_read_modify_write(struct file *file, struct folio *folio,
 	return false;
 }
 
-static struct folio *
-nfs_folio_grab_cache_write_begin(struct address_space *mapping, pgoff_t index)
-{
-	unsigned fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE;
-
-	return __filemap_get_folio(mapping, index, fgp_flags,
-				   mapping_gfp_mask(mapping));
-}
-
 /*
  * This does the "real" work of the write. We must allocate and lock the
  * page to be sent back to the generic routine, which then copies the
@@ -335,7 +326,8 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
 		file, mapping->host->i_ino, len, (long long) pos);
 
 start:
-	folio = nfs_folio_grab_cache_write_begin(mapping, pos >> PAGE_SHIFT);
+	folio = __filemap_get_folio(mapping, pos >> PAGE_SHIFT, FGP_WRITEBEGIN,
+				    mapping_gfp_mask(mapping));
 	if (!folio)
 		return -ENOMEM;
 	*pagep = &folio->page;