From e509ad4d77e6c8852f082104e388110d16fdfb97 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 14 Sep 2023 16:00:06 +0100 Subject: ext4: use bdev_getblk() to avoid memory reclaim in readahead path sb_getblk_gfp adds __GFP_NOFAIL, which is unnecessary for readahead; we're quite comfortable with the possibility that we may not get a bh back. Switch to bdev_getblk() which does not include __GFP_NOFAIL. Link: https://lkml.kernel.org/r/20230914150011.843330-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reported-by: Hui Zhu Closes: https://lore.kernel.org/linux-fsdevel/20230811035705.3296-1-teawaterz@linux.alibaba.com/ Signed-off-by: Andrew Morton --- fs/ext4/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/ext4/super.c') diff --git a/fs/ext4/super.c b/fs/ext4/super.c index dbebd8b3127e..268d812b0add 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -255,7 +255,8 @@ struct buffer_head *ext4_sb_bread_unmovable(struct super_block *sb, void ext4_sb_breadahead_unmovable(struct super_block *sb, sector_t block) { - struct buffer_head *bh = sb_getblk_gfp(sb, block, 0); + struct buffer_head *bh = bdev_getblk(sb->s_bdev, block, + sb->s_blocksize, GFP_NOWAIT); if (likely(bh)) { if (trylock_buffer(bh)) -- cgit v1.2.3 From 8a83ac54940d27b8f56d766e1cb270d150fedd50 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 14 Sep 2023 16:00:10 +0100 Subject: ext4: call bdev_getblk() from sb_getblk_gfp() Most of the callers of sb_getblk_gfp() already assumed that they were passing the entire GFP flags to use. Fix up the two callers that didn't, and remove the __GFP_NOFAIL from them since they both appear to correctly handle failure. Link: https://lkml.kernel.org/r/20230914150011.843330-8-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Hui Zhu Signed-off-by: Andrew Morton --- fs/ext4/super.c | 10 ++++++++-- include/linux/buffer_head.h | 6 +++--- 2 files changed, 11 insertions(+), 5 deletions(-) (limited to 'fs/ext4/super.c') diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 268d812b0add..c00ec159dea5 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -244,13 +244,19 @@ static struct buffer_head *__ext4_sb_bread_gfp(struct super_block *sb, struct buffer_head *ext4_sb_bread(struct super_block *sb, sector_t block, blk_opf_t op_flags) { - return __ext4_sb_bread_gfp(sb, block, op_flags, __GFP_MOVABLE); + gfp_t gfp = mapping_gfp_constraint(sb->s_bdev->bd_inode->i_mapping, + ~__GFP_FS) | __GFP_MOVABLE; + + return __ext4_sb_bread_gfp(sb, block, op_flags, gfp); } struct buffer_head *ext4_sb_bread_unmovable(struct super_block *sb, sector_t block) { - return __ext4_sb_bread_gfp(sb, block, 0, 0); + gfp_t gfp = mapping_gfp_constraint(sb->s_bdev->bd_inode->i_mapping, + ~__GFP_FS); + + return __ext4_sb_bread_gfp(sb, block, 0, gfp); } void ext4_sb_breadahead_unmovable(struct super_block *sb, sector_t block) diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index b294e2cccbae..22f13eece719 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -368,10 +368,10 @@ static inline struct buffer_head *sb_getblk(struct super_block *sb, return __getblk(sb->s_bdev, block, sb->s_blocksize); } -static inline struct buffer_head * -sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp) +static inline struct buffer_head *sb_getblk_gfp(struct super_block *sb, + sector_t block, gfp_t gfp) { - return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp); + return bdev_getblk(sb->s_bdev, block, sb->s_blocksize, gfp); } static inline struct buffer_head * -- cgit v1.2.3 From 1cbf0a58847b30507611f92ad69964ef37264d14 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 23 Oct 2023 23:26:08 -0700 Subject: ext4: add __GFP_NOWARN to GFP_NOWAIT in readahead Since commit e509ad4d77e6 ("ext4: use bdev_getblk() to avoid memory reclaim in readahead path") rightly replaced GFP_NOFAIL allocations by GFP_NOWAIT allocations, I've occasionally been seeing "page allocation failure: order:0" warnings under load: all with ext4_sb_breadahead_unmovable() in the stack. I don't think those warnings are of any interest: suppress them with __GFP_NOWARN. Link: https://lkml.kernel.org/r/7bc6ad16-9a4d-dd90-202e-47d6cbb5a136@google.com Fixes: e509ad4d77e6 ("ext4: use bdev_getblk() to avoid memory reclaim in readahead path") Signed-off-by: Hugh Dickins Reviewed-by: Jan Kara Cc: Hui Zhu Cc: Matthew Wilcox (Oracle) Cc: Theodore Ts'o Signed-off-by: Andrew Morton --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ext4/super.c') diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c00ec159dea5..56a08fc5c5d5 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -262,7 +262,7 @@ struct buffer_head *ext4_sb_bread_unmovable(struct super_block *sb, void ext4_sb_breadahead_unmovable(struct super_block *sb, sector_t block) { struct buffer_head *bh = bdev_getblk(sb->s_bdev, block, - sb->s_blocksize, GFP_NOWAIT); + sb->s_blocksize, GFP_NOWAIT | __GFP_NOWARN); if (likely(bh)) { if (trylock_buffer(bh)) -- cgit v1.2.3