[f2fs-dev] [PATCH 2/2] f2fs: quota: use memalloc_nofs_{save, restore} instead of FGP_NOFS

[Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

FGP_NOFS could be removed later, let's use memalloc_nofs_{save,restore}
instead, which is recommended to be used to avoid potential deadlock
when memory allocation in f2fs_quota_write() will call into filesystem
interface again, e.g. .writepages, evict_inode, shrinker due to
complicated lock race condition.

Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/f2fs/data.c  | 2 +-
 fs/f2fs/super.c | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index ac1cf4de3d62..be4c1d4ed6b2 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3994,7 +3994,7 @@ static int f2fs_write_begin(const struct kiocb *iocb,
 	 * Will wait that below with our IO control.
 	 */
 	folio = f2fs_filemap_get_folio(mapping, index,
-				FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_NOFS,
+				FGP_LOCK | FGP_WRITE | FGP_CREAT,
 				mapping_gfp_mask(mapping));
 	if (IS_ERR(folio)) {
 		err = PTR_ERR(folio);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index fdfd6a7203dd..d28a93657658 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3215,13 +3215,16 @@ static ssize_t f2fs_quota_write(struct super_block *sb, int type,
 	void *fsdata = NULL;
 	int err = 0;
 	int tocopy;
+	unsigned int nofs_flags;
 
 	while (towrite > 0) {
 		tocopy = min_t(unsigned long, sb->s_blocksize - offset,
 								towrite);
 retry:
+		nofs_flags = memalloc_nofs_save();
 		err = a_ops->write_begin(NULL, mapping, off, tocopy,
 							&folio, &fsdata);
+		memalloc_nofs_restore(nofs_flags);
 		if (unlikely(err)) {
 			if (err == -ENOMEM) {
 				memalloc_retry_wait(GFP_NOFS);
-- 
2.49.0



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