kernel/linux.git/block/bio.c, branch v7.3-rc1

block: introduce bio_iov_iter_set()

2026-08-15T23:09:32+00:00

In preparation to supporting dma-buf backed iterators and bios, introduce bio_iov_iter_set() which attempts to set up the bio directly from the given iterator. For now, it only supports bvec and expects users to check the result and fall back to other means if fails, but later we'll add more types. Suggested-by: Christoph Hellwig Signed-off-by: Pavel Begunkov Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/4686a0e47fc14f3f888967a80d45a6f66044f1e0.1785596451.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

block: move bvec init into __bio_clone

2026-08-15T23:09:32+00:00

Consolidate bi_io_vec assignment for cloning in __bio_clone to keep any further changes in one place. Suggested-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Signed-off-by: Pavel Begunkov Link: https://patch.msgid.link/6ecfe8f9b1c6bfb8665fba7daf55d9ad7a8a3243.1785596451.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

block: rename bi_bvec_done

2026-08-06T12:47:33+00:00

struct bvec_iter::bi_bvec_done is used an offset in the current bvec, let's rename it accordingly for better clarity. I also plan to use it for non-bvec based iteration in the future like dma-buf, so drop the "bvec" part. Suggested-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Signed-off-by: Pavel Begunkov Link: https://patch.msgid.link/4e4c21858705a200bd8848ffe4080522e3eb5c1c.1786018753.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

block: add task-context bio completion infrastructure

2026-07-31T15:00:14+00:00

Some bio completion handlers need to run from preemptible task context, but bio_endio() may be called from IRQ context (e.g., buffer_head writeback). Callers need a way to ensure their callback eventually runs from a sleepable context. Add infrastructure for that, in two forms: 1. BIO_COMPLETE_IN_TASK, a bio flag the submitter sets when it knows in advance that its callback needs task context (e.g., dropbehind writeback). bio_endio() sees the flag and offloads completion to a worker automatically. 2. bio_complete_in_task(), a helper that completion callbacks can invoke from within bi_end_io() when the deferral decision is dynamic (e.g., fserror reporting). Both share a per-CPU list drained by a work item on a WQ_PERCPU workqueue. Producers push the bio onto the local CPU's list and schedule the work item, which then dispatches each bio's bi_end_io() from task context. Both methods are gated on bio_in_atomic(), which returns true in any context where a sleeping bi_end_io() is unsafe, including non-preemptible task context. Two CPU hotplug callbacks are used to drain remaining bios from the departing CPU's batch, while maintaining the per-CPU behavior. The CPUHP_AP_ONLINE_DYN callback disables the per-CPU work item while the CPU is still online, preventing it from running on an unbound worker later. CPUHP_BP_PREPARE_DYN then drains any bios added between disabling the work item and CPU offline. Link: https://lore.kernel.org/all/20260409160243.1008358-1-hch@lst.de/ Suggested-by: Matthew Wilcox Suggested-by: Christoph Hellwig Signed-off-by: Tal Zussman Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/20260730-blk-dontcache-v7-2-3e8e6850068d@columbia.edu Signed-off-by: Jens Axboe

block: validate user space vectors during extraction

2026-07-31T14:10:49+00:00

The bio-based drivers don't necessarily check the alignment split, and stacking block drivers don't always handle a misalignment detected after submitting the bio. Validate user vectors against the device's dma_alignment as the bio is built from the iov_iter, rejecting misaligned early with -EINVAL. Cc: stable@vger.kernel.org Fixes: 5ff3f74e145a ("block: simplify direct io validity check") Fixes: 7eac33186957 ("iomap: simplify direct io validity check") Reviewed-by: Hannes Reinecke Reviewed-by: Christoph Hellwig Signed-off-by: Keith Busch Link: https://patch.msgid.link/20260720201057.1862857-6-kbusch@meta.com Signed-off-by: Jens Axboe

block: fix aligning of bounced dio read bios

2026-07-16T12:11:37+00:00

bio_iov_iter_align_down expects the "normal" biovec layout from vector 0, while bio_iov_iter_bounce_read abuses vector 0 for a bounce buffer allocation. Pass an explicit bvec to bio_iov_iter_align_down to deal with this case to avoid a double unpin. Additionally we need to free the folio if no bio_vec could be added, and adjust the size of the first bio_vec that contains the bounce buffer when the I/O size is aligned down. Fixes: e7b8b3c5b2a6 ("block: align down bounces bios") Reported-by: 0wnerD1ed Signed-off-by: Christoph Hellwig Tested-by: 0wnerD1ed Reviewed-by: Keith Busch Link: https://patch.msgid.link/20260716091306.316625-3-hch@lst.de Signed-off-by: Jens Axboe

block: handle huge zero folios in bio_free_folios

2026-07-16T12:11:37+00:00

When CONFIG_PERSISTENT_HUGE_ZERO_FOLIO is enabled, iomap_dio_zero() can add a huge zero folio to a zeroing bio, which needs special treatment in bio_free_folios by also checking is_huge_zero_folio() in addition to is_zero_folio(). Fixes: 8dd5e7c75d7b ("block: add helpers to bounce buffer an iov_iter into bios") Signed-off-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Link: https://patch.msgid.link/20260716091306.316625-2-hch@lst.de Signed-off-by: Jens Axboe

block: try slab allocation in bio_alloc_bioset() before mempool

2026-07-16T12:10:44+00:00

When the per-CPU bio cache is enabled but empty, bio_alloc_percpu_cache() returns NULL and bio_alloc_bioset() falls straight through to the mempool fallback: if (unlikely(!bio)) { if (!(saved_gfp & __GFP_DIRECT_RECLAIM)) return NULL; ... } For non-sleeping allocations (no __GFP_DIRECT_RECLAIM) this returns NULL without ever attempting a slab allocation, even when there is plenty of free memory. Commit b520c4eef83d ("block: split bio_alloc_bioset more clearly into a fast and slowpath") introduced this. Before it, a percpu cache miss fell through to mempool_alloc(), which attempted the underlying slab allocation first and only failed when that slab allocation failed. The restructuring dropped the slab attempt that non-sleeping callers of a cache-enabled bioset (such as the default fs_bio_set used by bio_alloc()) relied on. Try a slab allocation with optimistic GFP_ flags before falling back to the mempool whenever the bio is still NULL, so both the cache-empty and non-cache paths share the same slab attempt. This restores the previous behavior for non-sleeping allocations. Fixes: b520c4eef83d ("block: split bio_alloc_bioset more clearly into a fast and slowpath") Suggested-by: Christoph Hellwig Signed-off-by: Joseph Qi Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/20260709020145.4011533-1-joseph.qi@linux.alibaba.com Signed-off-by: Jens Axboe

block: do not warn when doing greedy allocation in folio_alloc_greedy()

2026-07-15T22:33:29+00:00

During one of my local btrfs fstests runs, folio_alloc() inside folio_alloc_greedy() triggered an allocation failure report when trying to allocate an order-4 folio. The kernel is from the latest development branch, which is utilizing the IOMAP_DIO_BOUNCE flag for direct writes when the inode requires checksum. Unfortunately I didn't save the full log, only the function and the order. When the IOMAP_DIO_BOUNCE flag is utilized, we will hit the following call chain: bio_iov_iter_bounce_write() |- folio_alloc_greedy() |- folio_alloc(gfp | __GFP_NORETRY, get_order(*size)); However __GFP_NORETRY will still emit an allocation failure report when it fails. And folio_alloc_greedy() will retry with a smaller order anyway, there is no point in emitting that allocation failure report. Append the __GFP_NOWARN flag to folio_alloc() for the larger-order folio attempts. Fixes: 8dd5e7c75d7b ("block: add helpers to bounce buffer an iov_iter into bios") Signed-off-by: Qu Wenruo Link: https://patch.msgid.link/d10571445ee505d95ba6eaad7558fc1f556d2921.1784020005.git.wqu@suse.com Signed-off-by: Jens Axboe

block: respect iov_iter::nofault flag in bio_iov_iter_bounce_write()

2026-06-16T20:48:35+00:00

For the incoming usage of IOMAP_DIO_BOUNCE in btrfs, btrfs has set iov_iter::nofault to prevent deadlock when a page fault is needed to read out the buffer. However bio_iov_iter_bounce_write() doesn't respect iov_iter::nofault flag, and just call a plain copy_from_iter() so it can still trigger page fault and cause deadlock in btrfs. Fix it by utilizing copy_folio_from_iter_atomic() if nofault flag is set, otherwise use copy_folio_from_iter(). Signed-off-by: Qu Wenruo Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/9c165a314022b61566eb247852eb773ca6c70889.1781597506.git.wqu@suse.com Signed-off-by: Jens Axboe