[PATCH v1 1/2] mm: rename AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM to AS_WRITEBACK_MAY_HANG

[Joanne Koong <joannelkoong@gmail.com>]

AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM was added to avoid waiting on
writeback during reclaim for inodes belonging to filesystems where
a) waiting on writeback in reclaim may lead to a deadlock or
b) a writeback request may never complete due to the nature of the
filesystem (unrelated to reclaim)

Rename AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM to the more generic
AS_WRITEBACK_MAY_HANG to reflect mappings where writeback may hang where
the cause could be unrelated to reclaim.

This allows us to later use AS_WRITEBACK_MAY_HANG to mitigate other
scenarios such as possible hangs when sync waits on writeback.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
---
 fs/fuse/file.c          |  2 +-
 include/linux/pagemap.h | 10 +++++-----
 mm/vmscan.c             |  3 +--
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f1ef77a0be05..0804c832bcb7 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3126,7 +3126,7 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags)
 	inode->i_fop = &fuse_file_operations;
 	inode->i_data.a_ops = &fuse_file_aops;
 	if (fc->writeback_cache)
-		mapping_set_writeback_may_deadlock_on_reclaim(&inode->i_data);
+		mapping_set_writeback_may_hang(&inode->i_data);
 
 	INIT_LIST_HEAD(&fi->write_files);
 	INIT_LIST_HEAD(&fi->queued_writes);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 09b581c1d878..a895d6b6aabb 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -210,7 +210,7 @@ enum mapping_flags {
 	AS_STABLE_WRITES = 7,	/* must wait for writeback before modifying
 				   folio contents */
 	AS_INACCESSIBLE = 8,	/* Do not attempt direct R/W access to the mapping */
-	AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM = 9,
+	AS_WRITEBACK_MAY_HANG = 9,
 	AS_KERNEL_FILE = 10,	/* mapping for a fake kernel file that shouldn't
 				   account usage to user cgroups */
 	/* Bits 16-25 are used for FOLIO_ORDER */
@@ -338,14 +338,14 @@ static inline bool mapping_inaccessible(const struct address_space *mapping)
 	return test_bit(AS_INACCESSIBLE, &mapping->flags);
 }
 
-static inline void mapping_set_writeback_may_deadlock_on_reclaim(struct address_space *mapping)
+static inline void mapping_set_writeback_may_hang(struct address_space *mapping)
 {
-	set_bit(AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM, &mapping->flags);
+	set_bit(AS_WRITEBACK_MAY_HANG, &mapping->flags);
 }
 
-static inline bool mapping_writeback_may_deadlock_on_reclaim(const struct address_space *mapping)
+static inline bool mapping_writeback_may_hang(const struct address_space *mapping)
 {
-	return test_bit(AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM, &mapping->flags);
+	return test_bit(AS_WRITEBACK_MAY_HANG, &mapping->flags);
 }
 
 static inline gfp_t mapping_gfp_mask(const struct address_space *mapping)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 92980b072121..636c18ee2b2c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1216,8 +1216,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
 			} else if (writeback_throttling_sane(sc) ||
 			    !folio_test_reclaim(folio) ||
 			    !may_enter_fs(folio, sc->gfp_mask) ||
-			    (mapping &&
-			     mapping_writeback_may_deadlock_on_reclaim(mapping))) {
+			    (mapping && mapping_writeback_may_hang(mapping))) {
 				/*
 				 * This is slightly racy -
 				 * folio_end_writeback() might have
-- 
2.47.3