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| author | Roman Gushchin <guro@fb.com> | 2020-02-28 16:14:11 -0800 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2020-04-15 23:58:48 -0400 |
| commit | d87f639258a6a5980183f11876c884931ad93da2 (patch) | |
| tree | f840887fbe136455b2eb47710c222018352f566c | |
| parent | c2a559bc0e7ed5a715ad6b947025b33cb7c05ea7 (diff) | |
| download | lwn-d87f639258a6a5980183f11876c884931ad93da2.tar.gz lwn-d87f639258a6a5980183f11876c884931ad93da2.zip | |
ext4: use non-movable memory for superblock readahead
Since commit a8ac900b8163 ("ext4: use non-movable memory for the
superblock") buffers for ext4 superblock were allocated using
the sb_bread_unmovable() helper which allocated buffer heads
out of non-movable memory blocks. It was necessarily to not block
page migrations and do not cause cma allocation failures.
However commit 85c8f176a611 ("ext4: preload block group descriptors")
broke this by introducing pre-reading of the ext4 superblock.
The problem is that __breadahead() is using __getblk() underneath,
which allocates buffer heads out of movable memory.
It resulted in page migration failures I've seen on a machine
with an ext4 partition and a preallocated cma area.
Fix this by introducing sb_breadahead_unmovable() and
__breadahead_gfp() helpers which use non-movable memory for buffer
head allocations and use them for the ext4 superblock readahead.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Fixes: 85c8f176a611 ("ext4: preload block group descriptors")
Signed-off-by: Roman Gushchin <guro@fb.com>
Link: https://lore.kernel.org/r/20200229001411.128010-1-guro@fb.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/buffer.c | 11 | ||||
| -rw-r--r-- | fs/ext4/inode.c | 2 | ||||
| -rw-r--r-- | fs/ext4/super.c | 2 | ||||
| -rw-r--r-- | include/linux/buffer_head.h | 8 |
4 files changed, 21 insertions, 2 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index f73276d746bb..599a0bf7257b 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1371,6 +1371,17 @@ void __breadahead(struct block_device *bdev, sector_t block, unsigned size) } EXPORT_SYMBOL(__breadahead); +void __breadahead_gfp(struct block_device *bdev, sector_t block, unsigned size, + gfp_t gfp) +{ + struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); + if (likely(bh)) { + ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh); + brelse(bh); + } +} +EXPORT_SYMBOL(__breadahead_gfp); + /** * __bread_gfp() - reads a specified block and returns the bh * @bdev: the block_device to read from diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 68f6c0af8e5d..2a4aae6acdcb 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4364,7 +4364,7 @@ make_io: if (end > table) end = table; while (b <= end) - sb_breadahead(sb, b++); + sb_breadahead_unmovable(sb, b++); } /* diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 9728e7b0e84f..83413f0f1e28 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4340,7 +4340,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) /* Pre-read the descriptors into the buffer cache */ for (i = 0; i < db_count; i++) { block = descriptor_loc(sb, logical_sb_block, i); - sb_breadahead(sb, block); + sb_breadahead_unmovable(sb, block); } for (i = 0; i < db_count; i++) { diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index e0b020eaf32e..15b765a181b8 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -189,6 +189,8 @@ struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block, void __brelse(struct buffer_head *); void __bforget(struct buffer_head *); void __breadahead(struct block_device *, sector_t block, unsigned int size); +void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size, + gfp_t gfp); struct buffer_head *__bread_gfp(struct block_device *, sector_t block, unsigned size, gfp_t gfp); void invalidate_bh_lrus(void); @@ -319,6 +321,12 @@ sb_breadahead(struct super_block *sb, sector_t block) __breadahead(sb->s_bdev, block, sb->s_blocksize); } +static inline void +sb_breadahead_unmovable(struct super_block *sb, sector_t block) +{ + __breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0); +} + static inline struct buffer_head * sb_getblk(struct super_block *sb, sector_t block) { |