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authorZhang Yi <yi.zhang@huawei.com>2022-09-01 21:34:53 +0800
committerAndrew Morton <akpm@linux-foundation.org>2022-09-11 20:26:06 -0700
commitfdee117ee86479fd2644bcd9ac2b2469e55722d1 (patch)
treea2a4e97bd7dbba96807d47d3f080e7a99281cf6d /include
parent214f8796907b8015b778badf4710a4701472779a (diff)
fs/buffer: add some new buffer read helpers
Current ll_rw_block() helper is fragile because it assumes that locked buffer means it's under IO which is submitted by some other who holds the lock, it skip buffer if it failed to get the lock, so it's only safe on the readahead path. Unfortunately, now that most filesystems still use this helper mistakenly on the sync metadata read path. There is no guarantee that the one who holds the buffer lock always submit IO (e.g. buffer_migrate_folio_norefs() after commit 88dbcbb3a484 ("blkdev: avoid migration stalls for blkdev pages"), it could lead to false positive -EIO when submitting reading IO. This patch add some friendly buffer read helpers to prepare replacing ll_rw_block() and similar calls. We can only call bh_readahead_[] helpers for the readahead paths. Link: https://lkml.kernel.org/r/20220901133505.2510834-3-yi.zhang@huawei.com Signed-off-by: Zhang Yi <yi.zhang@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/buffer_head.h38
1 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index c3863c417b00..6d09785bed9f 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -232,6 +232,9 @@ void write_boundary_block(struct block_device *bdev,
sector_t bblock, unsigned blocksize);
int bh_uptodate_or_lock(struct buffer_head *bh);
int bh_submit_read(struct buffer_head *bh);
+int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait);
+void __bh_read_batch(int nr, struct buffer_head *bhs[],
+ blk_opf_t op_flags, bool force_lock);
extern int buffer_heads_over_limit;
@@ -399,6 +402,41 @@ static inline struct buffer_head *__getblk(struct block_device *bdev,
return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
}
+static inline void bh_readahead(struct buffer_head *bh, blk_opf_t op_flags)
+{
+ if (!buffer_uptodate(bh) && trylock_buffer(bh)) {
+ if (!buffer_uptodate(bh))
+ __bh_read(bh, op_flags, false);
+ else
+ unlock_buffer(bh);
+ }
+}
+
+static inline void bh_read_nowait(struct buffer_head *bh, blk_opf_t op_flags)
+{
+ if (!bh_uptodate_or_lock(bh))
+ __bh_read(bh, op_flags, false);
+}
+
+/* Returns 1 if buffer uptodated, 0 on success, and -EIO on error. */
+static inline int bh_read(struct buffer_head *bh, blk_opf_t op_flags)
+{
+ if (bh_uptodate_or_lock(bh))
+ return 1;
+ return __bh_read(bh, op_flags, true);
+}
+
+static inline void bh_read_batch(int nr, struct buffer_head *bhs[])
+{
+ __bh_read_batch(nr, bhs, 0, true);
+}
+
+static inline void bh_readahead_batch(int nr, struct buffer_head *bhs[],
+ blk_opf_t op_flags)
+{
+ __bh_read_batch(nr, bhs, op_flags, false);
+}
+
/**
* __bread() - reads a specified block and returns the bh
* @bdev: the block_device to read from