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Wong" , Carlos Maiolino , Alexander Viro , Jan Kara Cc: Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Tal Zussman X-Mailer: b4 0.14.3-dev-d7477 X-Developer-Signature: v=1; a=ed25519-sha256; t=1774464193; l=4684; i=tz2294@columbia.edu; s=20250528; h=from:subject:message-id; bh=/KDtCfPcROGMHktI+sYIoy1sJXxmr+t5YwMIoFyxNlk=; b=yUgCWQ4ZcEeNTx5iojZlwuLJ75/zRFsFdFta96TVVGE0YTzeH6B4RKXjHrIwyFGw3hTK3rhgt gf2gbHu8FZ6CWKrHyJPeTOd+yuu9FyglPNZhfk8bDp7xeu7U5SJLlSh X-Developer-Key: i=tz2294@columbia.edu; a=ed25519; pk=BIj5KdACscEOyAC0oIkeZqLB3L94fzBnDccEooxeM5Y= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzI1MDE0MiBTYWx0ZWRfX65WlW+UiJx56 0SKoJnx1sULQ7fI1dy9nDpKG/N5UvQULb0TSWNbpRMPq3Mdwqe7AxFFNhGzbDN29UyUSmx4adFm 5Zdwz7N5RSgh/846AIFoMugbeCXAFO6e3OaiHI6UzN21z3VYxMmBOiFpfHBPN5FaOuHH7LYLyBV v0JHhZMsac9pyrXJT8AGKWG+GkUnHiEqOOExxk7Uw3FatJ3VnU0khWh8hFDc+4otKnsKWhQxEYE DyeqToj/HnUd53ybYVH0u4q4EugmkZZk6PXGFRo7Be1im+iLWTq3CMbOETN/0HgXyVS/p4tnYtU eHrkG2LCZXHrGsz+I1EhqFTKcHCsONuGf+LGWzeD+JmiASx5pvfvDmU0J86vmDR9nAmTtKutR9R g5vCic68smn/I8/M9Vn0atKsG/YP+qGQv1xL8Z9h03fdJPNR4lZ0qEXC6eCYJSj0KYCF7dw1+A5 mKxwAf0GvKl3O06L3Tw== X-Proofpoint-GUID: PeJIs6rHPYxV7D03TWrzIpt-pQYWFpZF X-Authority-Analysis: v=2.4 cv=ANMIVkx+ c=1 sm=1 tr=0 ts=69c437e1 cx=c_pps a=JbAStetqSzwMeJznSMzCyw==:117 a=QOUmeeuX5y9IvSxXHa6D2A==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=x7bEGLp0ZPQA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=azVShVRs0zEubeQ0wG0L:22 a=JfrnYn6hAAAA:8 a=QQSmTEQkt36Rj1JXOw4A:9 a=QEXdDO2ut3YA:10 a=uxP6HrT_eTzRwkO_Te1X:22 a=1CNFftbPRP8L7MoqJWF3:22 X-Proofpoint-ORIG-GUID: PeJIs6rHPYxV7D03TWrzIpt-pQYWFpZF X-Proofpoint-Virus-Version: vendor=nai engine=6800 definitions=11740 signatures=596818 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=10 suspectscore=0 phishscore=0 adultscore=0 priorityscore=1501 spamscore=0 malwarescore=0 impostorscore=10 bulkscore=10 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603250142 Some bio completion handlers need to run in task context but bio_endio() can be called from IRQ context (e.g. buffer_head writeback). Add a BIO_COMPLETE_IN_TASK flag that bio submitters can set to request task-context completion of their bi_end_io callback. When bio_endio() sees this flag and is running in non-task context, it queues the bio to a per-cpu list and schedules a work item to call bi_end_io() from task context. A CPU hotplug dead callback drains any remaining bios from the departing CPU's batch. This will be used to enable RWF_DONTCACHE for block devices, and could be used for other subsystems like fscrypt that need task-context bio completion. Suggested-by: Matthew Wilcox Signed-off-by: Tal Zussman --- block/bio.c | 84 +++++++++++++++++++++++++++++++++++++++++++= +++- include/linux/blk_types.h | 1 + 2 files changed, 84 insertions(+), 1 deletion(-) diff --git a/block/bio.c b/block/bio.c index 8203bb7455a9..69ee0d93041f 100644 --- a/block/bio.c +++ b/block/bio.c @@ -18,6 +18,7 @@ #include #include #include +#include =20 #include #include "blk.h" @@ -1714,6 +1715,60 @@ void bio_check_pages_dirty(struct bio *bio) } EXPORT_SYMBOL_GPL(bio_check_pages_dirty); =20 +struct bio_complete_batch { + local_lock_t lock; + struct bio_list list; + struct work_struct work; +}; + +static DEFINE_PER_CPU(struct bio_complete_batch, bio_complete_batch) =3D { + .lock =3D INIT_LOCAL_LOCK(lock), +}; + +static void bio_complete_work_fn(struct work_struct *w) +{ + struct bio_complete_batch *batch; + struct bio_list list; + +again: + local_lock_irq(&bio_complete_batch.lock); + batch =3D this_cpu_ptr(&bio_complete_batch); + list =3D batch->list; + bio_list_init(&batch->list); + local_unlock_irq(&bio_complete_batch.lock); + + while (!bio_list_empty(&list)) { + struct bio *bio =3D bio_list_pop(&list); + bio->bi_end_io(bio); + } + + local_lock_irq(&bio_complete_batch.lock); + batch =3D this_cpu_ptr(&bio_complete_batch); + if (!bio_list_empty(&batch->list)) { + local_unlock_irq(&bio_complete_batch.lock); + + if (!need_resched()) + goto again; + + schedule_work_on(smp_processor_id(), &batch->work); + return; + } + local_unlock_irq(&bio_complete_batch.lock); +} + +static void bio_queue_completion(struct bio *bio) +{ + struct bio_complete_batch *batch; + unsigned long flags; + + local_lock_irqsave(&bio_complete_batch.lock, flags); + batch =3D this_cpu_ptr(&bio_complete_batch); + bio_list_add(&batch->list, bio); + local_unlock_irqrestore(&bio_complete_batch.lock, flags); + + schedule_work_on(smp_processor_id(), &batch->work); +} + static inline bool bio_remaining_done(struct bio *bio) { /* @@ -1788,7 +1843,9 @@ void bio_endio(struct bio *bio) } #endif =20 - if (bio->bi_end_io) + if (!in_task() && bio_flagged(bio, BIO_COMPLETE_IN_TASK)) + bio_queue_completion(bio); + else if (bio->bi_end_io) bio->bi_end_io(bio); } EXPORT_SYMBOL(bio_endio); @@ -1974,6 +2031,21 @@ int bioset_init(struct bio_set *bs, } EXPORT_SYMBOL(bioset_init); =20 +/* + * Drain a dead CPU's deferred bio completions. The CPU is dead so no lock= ing + * is needed -- no new bios will be queued to it. + */ +static int bio_complete_batch_cpu_dead(unsigned int cpu) +{ + struct bio_complete_batch *batch =3D per_cpu_ptr(&bio_complete_batch, cpu= ); + struct bio *bio; + + while ((bio =3D bio_list_pop(&batch->list))) + bio->bi_end_io(bio); + + return 0; +} + static int __init init_bio(void) { int i; @@ -1988,6 +2060,16 @@ static int __init init_bio(void) SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); } =20 + for_each_possible_cpu(i) { + struct bio_complete_batch *batch =3D + per_cpu_ptr(&bio_complete_batch, i); + + bio_list_init(&batch->list); + INIT_WORK(&batch->work, bio_complete_work_fn); + } + + cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "block/bio:complete:dead", + NULL, bio_complete_batch_cpu_dead); cpuhp_setup_state_multi(CPUHP_BIO_DEAD, "block/bio:dead", NULL, bio_cpu_dead); =20 diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 8808ee76e73c..d49d97a050d0 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -322,6 +322,7 @@ enum { BIO_REMAPPED, BIO_ZONE_WRITE_PLUGGING, /* bio handled through zone write plugging */ BIO_EMULATES_ZONE_APPEND, /* bio emulates a zone append operation */ + BIO_COMPLETE_IN_TASK, /* complete bi_end_io() in task context */ BIO_FLAG_LAST }; 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Wong" , Carlos Maiolino , Alexander Viro , Jan Kara Cc: Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Tal Zussman X-Mailer: b4 0.14.3-dev-d7477 X-Developer-Signature: v=1; a=ed25519-sha256; t=1774464193; l=1665; i=tz2294@columbia.edu; s=20250528; h=from:subject:message-id; bh=7zwsmyUip3CAkS6JVcgPiuvcXkqOuFIklXcl4CKLS7s=; b=L4CWzIK6kHXuFczj/fPjz2aWyUnS1OpJUL3M+esbeR43gMhMyjhAVsUMhpLPiY2zQSiPsjHza J5C73e08cUYBjjsRFhFa/ta9SjUn5dInI/J4XLjlsu/GNzv1JM0+xWE X-Developer-Key: i=tz2294@columbia.edu; a=ed25519; pk=BIj5KdACscEOyAC0oIkeZqLB3L94fzBnDccEooxeM5Y= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzI1MDE0MiBTYWx0ZWRfX7rXXkwA6QOy6 GIRr4woykgkQN9rjh9czb8V87s6b9sRUCYxV9RnOovzI1oWrRULYvSVZ8FmtvBBegTSEXaQDXDE UKVwyESt7gMO5J5STjMXJRKjbkCZ0+hOpNEMMdpW9W/eaGu5jvulHwVq68i4Db5HblVu58yIHPo 9Dei4MZHHPruihVvMn/aqpmzQG+Zb+Zlt/Kq/YLiD0l0FAPkU5t3I5Ty7yzgy+5TIzNCD7mejY7 1SS30sKm1CZ2fgPdE/tgNyTaiUQSEVTaTl32lA8m/yxPavu2BwT8BYnf2yEkNhrxRXiV/yAiXrB afi019TQBwZmgduv4xpfrWKGATYeBwXTQTh1l76u8JCK4R3LzXa605t7UxbRa9MDa51tKWTjpIJ JhXSRUq/w0Qh+fqJlY+SQwPfX8C6i8ei6sfULctq4tg1sAZgjDDGcis/t/Ar2Y0W6UgwX+IjSc2 p/Jb3PoIQL0skF9bypA== X-Proofpoint-GUID: c5U2V4_zUz5ZRDqeXTDBmyNlbTqJZpFh X-Authority-Analysis: v=2.4 cv=ANMIVkx+ c=1 sm=1 tr=0 ts=69c437e2 cx=c_pps a=mPf7EqFMSY9/WdsSgAYMbA==:117 a=QOUmeeuX5y9IvSxXHa6D2A==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=x7bEGLp0ZPQA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=azVShVRs0zEubeQ0wG0L:22 a=wJ0dTj9p17mGQU10CegA:9 a=QEXdDO2ut3YA:10 a=dawVfQjAaf238kedN5IG:22 X-Proofpoint-ORIG-GUID: c5U2V4_zUz5ZRDqeXTDBmyNlbTqJZpFh X-Proofpoint-Virus-Version: vendor=nai engine=6800 definitions=11740 signatures=596818 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=10 suspectscore=0 phishscore=0 adultscore=0 priorityscore=1501 spamscore=0 malwarescore=0 impostorscore=10 bulkscore=10 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603250142 Set BIO_COMPLETE_IN_TASK on iomap writeback bios when IOMAP_IOEND_DONTCACHE is set. This ensures that bi_end_io runs in task context, where folio_end_dropbehind() can safely invalidate folios. With the bio layer now handling task-context deferral generically, XFS no longer needs to route DONTCACHE ioends through its completion workqueue for page cache invalidation. Remove the DONTCACHE check from xfs_ioend_needs_wq_completion(). Signed-off-by: Tal Zussman --- fs/iomap/ioend.c | 2 ++ fs/xfs/xfs_aops.c | 4 ---- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/fs/iomap/ioend.c b/fs/iomap/ioend.c index e4d57cb969f1..6b8375d11cc0 100644 --- a/fs/iomap/ioend.c +++ b/fs/iomap/ioend.c @@ -113,6 +113,8 @@ static struct iomap_ioend *iomap_alloc_ioend(struct iom= ap_writepage_ctx *wpc, GFP_NOFS, &iomap_ioend_bioset); bio->bi_iter.bi_sector =3D iomap_sector(&wpc->iomap, pos); bio->bi_write_hint =3D wpc->inode->i_write_hint; + if (ioend_flags & IOMAP_IOEND_DONTCACHE) + bio_set_flag(bio, BIO_COMPLETE_IN_TASK); wbc_init_bio(wpc->wbc, bio); wpc->nr_folios =3D 0; return iomap_init_ioend(wpc->inode, bio, pos, ioend_flags); diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 76678814f46f..0d469b91377d 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -510,10 +510,6 @@ xfs_ioend_needs_wq_completion( if (ioend->io_flags & (IOMAP_IOEND_UNWRITTEN | IOMAP_IOEND_SHARED)) return true; =20 - /* Page cache invalidation cannot be done in irq context. */ - if (ioend->io_flags & IOMAP_IOEND_DONTCACHE) - return true; 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Wong" , Carlos Maiolino , Alexander Viro , Jan Kara Cc: Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Tal Zussman X-Mailer: b4 0.14.3-dev-d7477 X-Developer-Signature: v=1; a=ed25519-sha256; t=1774464193; l=4833; i=tz2294@columbia.edu; s=20250528; h=from:subject:message-id; bh=vqYjVe4t0i/AiFArpSZ9mEXLlU4rnE2ZRBBMSnozEZ0=; b=gpmN0bZuDH/LOZGTVX2LWTAbwaNFAVtx+0hCaa/06cmF7hrJjYYHDM3SkZtVNTBPzJKHCu1Ro uxYVg0q9qKMB8UfKgMIhJOiUIQQkEPxysztQm+QmC6XaBib3Uj2eKTq X-Developer-Key: i=tz2294@columbia.edu; a=ed25519; pk=BIj5KdACscEOyAC0oIkeZqLB3L94fzBnDccEooxeM5Y= X-Proofpoint-GUID: PdV94sjV4bTLrUgb6GV21sb-HleDYBkA X-Proofpoint-ORIG-GUID: PdV94sjV4bTLrUgb6GV21sb-HleDYBkA X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzI1MDE0MiBTYWx0ZWRfXz/VVIsgqp3lA 0sXGw3UUDzyEbTyH73OPPwGnm+VUYr1xSksvue+1a8QYZ3lSMaNeOIgrWpoPQTqugpOZ2uxHkXX gN1xSixSKscLrYjlNqrb6pJ4WHYGFox1B6N8EqZYFTpwlwqzSGxB2h4Bkz0cG3BhdIK8Ue/lDup 0SqgODytbFRh/SdeqcSUdAd5RU148OlBRHfvfHmzUSeZh8uinwPHXYrvXAPg+Rb/J9bWiw5InYh 0bk9QMmE9+iTSTK3ng6s1gP5QmYCgSITn0skO/mfkn6Jh37Zlw/vJYH/6SgVKcSdDHG1ITFRNr3 yCsoND2fYaD0SvO9O27sEcsoWxZkvxGv48Q50a/cWBtgOm5z1+lAvgVFq4eDqCWB3mm17gL0do5 kbtPM9vhsR/WYpMHuH6NN5J29o2toO42u22t3oXD2wPv4DSkzWHrUTNy1c2gL3EE0jzeTH5rSPj 56C3v0dWN1XFEjeNDBA== X-Authority-Analysis: v=2.4 cv=JMw2csKb c=1 sm=1 tr=0 ts=69c437e3 cx=c_pps a=WeENfcodrlLV9YRTxbY/uA==:117 a=QOUmeeuX5y9IvSxXHa6D2A==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=x7bEGLp0ZPQA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=HpS3TJQ9O3Ob1ozEcmik:22 a=KmSSIXLuV57r0wwE8Y4A:9 a=QEXdDO2ut3YA:10 a=kacYvNCVWA4VmyqE58fU:22 X-Proofpoint-Virus-Version: vendor=nai engine=6800 definitions=11740 signatures=596818 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 impostorscore=10 suspectscore=0 adultscore=0 phishscore=0 spamscore=0 malwarescore=0 bulkscore=10 lowpriorityscore=10 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603250142 Block device buffered reads and writes already pass through filemap_read() and iomap_file_buffered_write() respectively, both of which handle IOCB_DONTCACHE. Enable RWF_DONTCACHE for block device files by setting FOP_DONTCACHE in def_blk_fops. For CONFIG_BUFFER_HEAD=3Dy paths, add block_write_begin_iocb() which threads the kiocb through so that buffer_head-based I/O can use DONTCACHE behavior. 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 so that buffer_head writeback completions get deferred to task context. CONFIG_BUFFER_HEAD=3Dn paths are handled by the previously added iomap BIO_COMPLETE_IN_TASK support. This support is useful for databases that operate on raw block devices, among other userspace applications. Signed-off-by: Tal Zussman --- block/fops.c | 5 +++-- fs/buffer.c | 22 +++++++++++++++++++--- include/linux/buffer_head.h | 3 +++ 3 files changed, 25 insertions(+), 5 deletions(-) diff --git a/block/fops.c b/block/fops.c index 4d32785b31d9..d8165f6ba71c 100644 --- a/block/fops.c +++ b/block/fops.c @@ -505,7 +505,8 @@ static int blkdev_write_begin(const struct kiocb *iocb, unsigned len, struct folio **foliop, void **fsdata) { - return block_write_begin(mapping, pos, len, foliop, blkdev_get_block); + return block_write_begin_iocb(iocb, mapping, pos, len, foliop, + blkdev_get_block); } =20 static int blkdev_write_end(const struct kiocb *iocb, @@ -967,7 +968,7 @@ const struct file_operations def_blk_fops =3D { .splice_write =3D iter_file_splice_write, .fallocate =3D blkdev_fallocate, .uring_cmd =3D blkdev_uring_cmd, - .fop_flags =3D FOP_BUFFER_RASYNC, + .fop_flags =3D FOP_BUFFER_RASYNC | FOP_DONTCACHE, }; =20 static __init int blkdev_init(void) diff --git a/fs/buffer.c b/fs/buffer.c index ed724a902657..c60c0ad6cc35 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2239,14 +2239,19 @@ 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 =3D pos >> PAGE_SHIFT; + fgf_t fgp_flags =3D FGP_WRITEBEGIN; struct folio *folio; int status; =20 - folio =3D __filemap_get_folio(mapping, index, FGP_WRITEBEGIN, + if (iocb && iocb->ki_flags & IOCB_DONTCACHE) + fgp_flags |=3D FGP_DONTCACHE; + + folio =3D __filemap_get_folio(mapping, index, fgp_flags, mapping_gfp_mask(mapping)); if (IS_ERR(folio)) return PTR_ERR(folio); @@ -2261,6 +2266,13 @@ int block_write_begin(struct address_space *mapping,= loff_t pos, unsigned len, *foliop =3D 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); =20 int block_write_end(loff_t pos, unsigned len, unsigned copied, @@ -2589,7 +2601,8 @@ int cont_write_begin(const struct kiocb *iocb, struct= address_space *mapping, (*bytes)++; } =20 - return block_write_begin(mapping, pos, len, foliop, get_block); + return block_write_begin_iocb(iocb, mapping, pos, len, foliop, + get_block); } EXPORT_SYMBOL(cont_write_begin); =20 @@ -2801,6 +2814,9 @@ static void submit_bh_wbc(blk_opf_t opf, struct buffe= r_head *bh, =20 bio =3D bio_alloc(bh->b_bdev, 1, opf, GFP_NOIO); =20 + if (folio_test_dropbehind(bh->b_folio)) + bio_set_flag(bio, BIO_COMPLETE_IN_TASK); + fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO); =20 bio->bi_iter.bi_sector =3D bh->b_blocknr * (bh->b_size >> 9); diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index b16b88bfbc3e..ddf88ce290f2 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 foli= o *); --=20 2.39.5