Add block_write_begin_iocb() which threads the kiocb through to __filemap_get_folio() so that buffer_head-based I/O can use DONTCACHE behavior. When the iocb has IOCB_DONTCACHE set, FGP_DONTCACHE is passed to mark the folio for dropbehind. The existing block_write_begin() is preserved as a wrapper that passes a NULL iocb. Set BIO_COMPLETE_IN_TASK in submit_bh_wbc() when the folio has dropbehind set, so that buffer_head writeback completions get deferred to task context. Signed-off-by: Tal Zussman --- fs/buffer.c | 19 +++++++++++++++++-- include/linux/buffer_head.h | 3 +++ 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index b0b3792b1496..d0abaf44d782 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2138,14 +2138,19 @@ EXPORT_SYMBOL(block_commit_write); * * The filesystem needs to handle block truncation upon failure. */ -int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, +int block_write_begin_iocb(const struct kiocb *iocb, + struct address_space *mapping, loff_t pos, unsigned len, struct folio **foliop, get_block_t *get_block) { pgoff_t index = pos >> PAGE_SHIFT; + fgf_t fgp_flags = FGP_WRITEBEGIN; struct folio *folio; int status; - folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN, + if (iocb && iocb->ki_flags & IOCB_DONTCACHE) + fgp_flags |= FGP_DONTCACHE; + + folio = __filemap_get_folio(mapping, index, fgp_flags, mapping_gfp_mask(mapping)); if (IS_ERR(folio)) return PTR_ERR(folio); @@ -2160,6 +2165,13 @@ int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, *foliop = folio; return status; } + +int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, + struct folio **foliop, get_block_t *get_block) +{ + return block_write_begin_iocb(NULL, mapping, pos, len, foliop, + get_block); +} EXPORT_SYMBOL(block_write_begin); int block_write_end(loff_t pos, unsigned len, unsigned copied, @@ -2715,6 +2727,9 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh, bio = bio_alloc(bh->b_bdev, 1, opf, GFP_NOIO); + if (folio_test_dropbehind(bh->b_folio)) + bio_set_flag(bio, BIO_COMPLETE_IN_TASK); + if (IS_ENABLED(CONFIG_FS_ENCRYPTION)) buffer_set_crypto_ctx(bio, bh, GFP_NOIO); diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index e4939e33b4b5..4ce50882d621 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -260,6 +260,9 @@ int block_read_full_folio(struct folio *, get_block_t *); bool block_is_partially_uptodate(struct folio *, size_t from, size_t count); int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, struct folio **foliop, get_block_t *get_block); +int block_write_begin_iocb(const struct kiocb *iocb, + struct address_space *mapping, loff_t pos, unsigned len, + struct folio **foliop, get_block_t *get_block); int __block_write_begin(struct folio *folio, loff_t pos, unsigned len, get_block_t *get_block); int block_write_end(loff_t pos, unsigned len, unsigned copied, struct folio *); -- 2.39.5