// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/ext4/page-io.c * * This contains the new page_io functions for ext4 * * Written by Theodore Ts'o, 2010. */ #include <linux/fs.h> #include <linux/time.h> #include <linux/highuid.h> #include <linux/pagemap.h> #include <linux/quotaops.h> #include <linux/string.h> #include <linux/buffer_head.h> #include <linux/writeback.h> #include <linux/pagevec.h> #include <linux/mpage.h> #include <linux/namei.h> #include <linux/uio.h> #include <linux/bio.h> #include <linux/workqueue.h> #include <linux/kernel.h> #include <linux/slab.h> #include <linux/mm.h> #include <linux/sched/mm.h> #include "ext4_jbd2.h" #include "xattr.h" #include "acl.h" static struct kmem_cache *io_end_cachep; static struct kmem_cache *io_end_vec_cachep; int __init ext4_init_pageio(void) { io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT); if (io_end_cachep == NULL) return -ENOMEM; io_end_vec_cachep = KMEM_CACHE(ext4_io_end_vec, 0); if (io_end_vec_cachep == NULL) { kmem_cache_destroy(io_end_cachep); return -ENOMEM; } return 0; } void ext4_exit_pageio(void) { kmem_cache_destroy(io_end_cachep); kmem_cache_destroy(io_end_vec_cachep); } struct ext4_io_end_vec *ext4_alloc_io_end_vec(ext4_io_end_t *io_end) { struct ext4_io_end_vec *io_end_vec; io_end_vec = kmem_cache_zalloc(io_end_vec_cachep, GFP_NOFS); if (!io_end_vec) return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&io_end_vec->list); list_add_tail(&io_end_vec->list, &io_end->list_vec); return io_end_vec; } static void ext4_free_io_end_vec(ext4_io_end_t *io_end) { struct ext4_io_end_vec *io_end_vec, *tmp; if (list_empty(&io_end->list_vec)) return; list_for_each_entry_safe(io_end_vec, tmp, &io_end->list_vec, list) { list_del(&io_end_vec->list); kmem_cache_free(io_end_vec_cachep, io_end_vec); } } struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end) { BUG_ON(list_empty(&io_end->list_vec)); return list_last_entry(&io_end->list_vec, struct ext4_io_end_vec, list); } /* * Print an buffer I/O error compatible with the fs/buffer.c. This * provides compatibility with dmesg scrapers that look for a specific * buffer I/O error message. We really need a unified error reporting * structure to userspace ala Digital Unix's uerf system, but it's * probably not going to happen in my lifetime, due to LKML politics... */ static void buffer_io_error(struct buffer_head *bh) { printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n", bh->b_bdev, (unsigned long long)bh->b_blocknr); } static void ext4_finish_bio(struct bio *bio) { struct bio_vec *bvec; struct bvec_iter_all iter_all; bio_for_each_segment_all(bvec, bio, iter_all) { struct page *page = bvec->bv_page; struct page *bounce_page = NULL; struct buffer_head *bh, *head; unsigned bio_start = bvec->bv_offset; unsigned bio_end = bio_start + bvec->bv_len; unsigned under_io = 0; unsigned long flags; if (fscrypt_is_bounce_page(page)) { bounce_page = page; page = fscrypt_pagecache_page(bounce_page); } if (bio->bi_status) { SetPageError(page); mapping_set_error(page->mapping, -EIO); } bh = head = page_buffers(page); /* * We check all buffers in the page under b_uptodate_lock * to avoid races with other end io clearing async_write flags */ spin_lock_irqsave(&head->b_uptodate_lock, flags); do { if (bh_offset(bh) < bio_start || bh_offset(bh) + bh->b_size > bio_end) { if (buffer_async_write(bh)) under_io++; continue; } clear_buffer_async_write(bh); if (bio->bi_status) { set_buffer_write_io_error(bh); buffer_io_error(bh); } } while ((bh = bh->b_this_page) != head); spin_unlock_irqrestore(&head->b_uptodate_lock, flags); if (!under_io) { fscrypt_free_bounce_page(bounce_page); end_page_writeback(page); } } } static void ext4_release_io_end(ext4_io_end_t *io_end) { struct bio *bio, *next_bio; BUG_ON(!list_empty(&io_end->list)); BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN); WARN_ON(io_end->handle); for (bio = io_end->bio; bio; bio = next_bio) { next_bio = bio->bi_private; ext4_finish_bio(bio); bio_put(bio); } ext4_free_io_end_vec(io_end); kmem_cache_free(io_end_cachep, io_end); } /* * Check a range of space and convert unwritten extents to written. Note that * we are protected from truncate touching same part of extent tree by the * fact that truncate code waits for all DIO to finish (thus exclusion from * direct IO is achieved) and also waits for PageWriteback bits. Thus we * cannot get to ext4_ext_truncate() before all IOs overlapping that range are * completed (happens from ext4_free_ioend()). */ static int ext4_end_io_end(ext4_io_end_t *io_end) { struct inode *inode = io_end->inode; handle_t *handle = io_end->handle; int ret = 0; ext4_debug("ext4_end_io_nolock: io_end 0x%p from inode %lu,list->next 0x%p," "list->prev 0x%p\n", io_end, inode->i_ino, io_end->list.next, io_end->list.prev); io_end->handle = NULL; /* Following call will use up the handle */ ret = ext4_convert_unwritten_io_end_vec(handle, io_end); if (ret < 0 && !ext4_forced_shutdown(EXT4_SB(inode->i_sb))) { ext4_msg(inode->i_sb, KERN_EMERG, "failed to convert unwritten extents to written " "extents -- potential data loss! " "(inode %lu, error %d)", inode->i_ino, ret); } ext4_clear_io_unwritten_flag(io_end); ext4_release_io_end(io_end); return ret; } static void dump_completed_IO(struct inode *inode, struct list_head *head) { #ifdef EXT4FS_DEBUG struct list_head *cur, *before, *after; ext4_io_end_t *io_end, *io_end0, *io_end1; if (list_empty(head)) return; ext4_debug("Dump inode %lu completed io list\n", inode->i_ino); list_for_each_entry(io_end, head, list) { cur = &io_end->list; before = cur->prev; io_end0 = container_of(before, ext4_io_end_t, list); after = cur->next; io_end1 = container_of(after, ext4_io_end_t, list); ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n", io_end, inode->i_ino, io_end0, io_end1); } #endif } /* Add the io_end to per-inode completed end_io list. */ static void ext4_add_complete_io(ext4_io_end_t *io_end) { struct ext4_inode_info *ei = EXT4_I(io_end->inode); struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb); struct workqueue_struct *wq; unsigned long flags; /* Only reserved conversions from writeback should enter here */ WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN)); WARN_ON(!io_end->handle && sbi->s_journal); spin_lock_irqsave(&ei->i_completed_io_lock, flags); wq = sbi->rsv_conversion_wq; if (list_empty(&ei->i_rsv_conversion_list)) queue_work(wq, &ei->i_rsv_conversion_work); list_add_tail(&io_end->list, &ei->i_rsv_conversion_list); spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); } static int ext4_do_flush_completed_IO(struct inode *inode, struct list_head *head) { ext4_io_end_t *io_end; struct list_head unwritten; unsigned long flags; struct ext4_inode_info *ei = EXT4_I(inode); int err, ret = 0; spin_lock_irqsave(&ei->i_completed_io_lock, flags); dump_completed_IO(inode, head); list_replace_init(head, &unwritten); spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); while (!list_empty(&unwritten)) { io_end = list_entry(unwritten.next, ext4_io_end_t, list); BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN)); list_del_init(&io_end->list); err = ext4_end_io_end(io_end); if (unlikely(!ret && err)) ret = err; } return ret; } /* * work on completed IO, to convert unwritten extents to extents */ void ext4_end_io_rsv_work(struct work_struct *work) { struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info, i_rsv_conversion_work); ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list); } ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags) { ext4_io_end_t *io_end = kmem_cache_zalloc(io_end_cachep, flags); if (io_end) { io_end->inode = inode; INIT_LIST_HEAD(&io_end->list); INIT_LIST_HEAD(&io_end->list_vec); refcount_set(&io_end->count, 1); } return io_end; } void ext4_put_io_end_defer(ext4_io_end_t *io_end) { if (refcount_dec_and_test(&io_end->count)) { if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || list_empty(&io_end->list_vec)) { ext4_release_io_end(io_end); return; } ext4_add_complete_io(io_end); } } int ext4_put_io_end(ext4_io_end_t *io_end) { int err = 0; if (refcount_dec_and_test(&io_end->count)) { if (io_end->flag & EXT4_IO_END_UNWRITTEN) { err = ext4_convert_unwritten_io_end_vec(io_end->handle, io_end); io_end->handle = NULL; ext4_clear_io_unwritten_flag(io_end); } ext4_release_io_end(io_end); } return err; } ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end) { refcount_inc(&io_end->count); return io_end; } /* BIO completion function for page writeback */ static void ext4_end_bio(struct bio *bio) { ext4_io_end_t *io_end = bio->bi_private; sector_t bi_sector = bio->bi_iter.bi_sector; if (WARN_ONCE(!io_end, "io_end is NULL: %pg: sector %Lu len %u err %d\n", bio->bi_bdev, (long long) bio->bi_iter.bi_sector, (unsigned) bio_sectors(bio), bio->bi_status)) { ext4_finish_bio(bio); bio_put(bio); return; } bio->bi_end_io = NULL; if (bio->bi_status) { struct inode *inode = io_end->inode; ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu " "starting block %llu)", bio->bi_status, inode->i_ino, (unsigned long long) bi_sector >> (inode->i_blkbits - 9)); mapping_set_error(inode->i_mapping, blk_status_to_errno(bio->bi_status)); } if (io_end->flag & EXT4_IO_END_UNWRITTEN) { /* * Link bio into list hanging from io_end. We have to do it * atomically as bio completions can be racing against each * other. */ bio->bi_private = xchg(&io_end->bio, bio); ext4_put_io_end_defer(io_end); } else { /* * Drop io_end reference early. Inode can get freed once * we finish the bio. */ ext4_put_io_end_defer(io_end); ext4_finish_bio(bio); bio_put(bio); } } void ext4_io_submit(struct ext4_io_submit *io) { struct bio *bio = io->io_bio; if (bio) { if (io->io_wbc->sync_mode == WB_SYNC_ALL) io->io_bio->bi_opf |= REQ_SYNC; submit_bio(io->io_bio); } io->io_bio = NULL; } void ext4_io_submit_init(struct ext4_io_submit *io, struct writeback_control *wbc) { io->io_wbc = wbc; io->io_bio = NULL; io->io_end = NULL; } static void io_submit_init_bio(struct ext4_io_submit *io, struct buffer_head *bh) { struct bio *bio; /* * bio_alloc will _always_ be able to allocate a bio if * __GFP_DIRECT_RECLAIM is set, see comments for bio_alloc_bioset(). */ bio = bio_alloc(bh->b_bdev, BIO_MAX_VECS, REQ_OP_WRITE, GFP_NOIO); fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO); bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); bio->bi_end_io = ext4_end_bio; bio->bi_private = ext4_get_io_end(io->io_end); io->io_bio = bio; io->io_next_block = bh->b_blocknr; wbc_init_bio(io->io_wbc, bio); } static void io_submit_add_bh(struct ext4_io_submit *io, struct inode *inode, struct page *pagecache_page, struct page *bounce_page, struct buffer_head *bh) { int ret; if (io->io_bio && (bh->b_blocknr != io->io_next_block || !fscrypt_mergeable_bio_bh(io->io_bio, bh))) { submit_and_retry: ext4_io_submit(io); } if (io->io_bio == NULL) io_submit_init_bio(io, bh); ret = bio_add_page(io->io_bio, bounce_page ?: pagecache_page, bh->b_size, bh_offset(bh)); if (ret != bh->b_size) goto submit_and_retry; wbc_account_cgroup_owner(io->io_wbc, pagecache_page, bh->b_size); io->io_next_block++; } int ext4_bio_write_page(struct ext4_io_submit *io, struct page *page, int len, bool keep_towrite) { struct page *bounce_page = NULL; struct inode *inode = page->mapping->host; unsigned block_start; struct buffer_head *bh, *head; int ret = 0; int nr_submitted = 0; int nr_to_submit = 0; struct writeback_control *wbc = io->io_wbc; BUG_ON(!PageLocked(page)); BUG_ON(PageWriteback(page)); if (keep_towrite) set_page_writeback_keepwrite(page); else set_page_writeback(page); ClearPageError(page); /* * Comments copied from block_write_full_page: * * The page straddles i_size. It must be zeroed out on each and every * writepage invocation because it may be mmapped. "A file is mapped * in multiples of the page size. For a file that is not a multiple of * the page size, the remaining memory is zeroed when mapped, and * writes to that region are not written out to the file." */ if (len < PAGE_SIZE) zero_user_segment(page, len, PAGE_SIZE); /* * In the first loop we prepare and mark buffers to submit. We have to * mark all buffers in the page before submitting so that * end_page_writeback() cannot be called from ext4_end_bio() when IO * on the first buffer finishes and we are still working on submitting * the second buffer. */ bh = head = page_buffers(page); do { block_start = bh_offset(bh); if (block_start >= len) { clear_buffer_dirty(bh); set_buffer_uptodate(bh); continue; } if (!buffer_dirty(bh) || buffer_delay(bh) || !buffer_mapped(bh) || buffer_unwritten(bh)) { /* A hole? We can safely clear the dirty bit */ if (!buffer_mapped(bh)) clear_buffer_dirty(bh); if (io->io_bio) ext4_io_submit(io); continue; } if (buffer_new(bh)) clear_buffer_new(bh); set_buffer_async_write(bh); nr_to_submit++; } while ((bh = bh->b_this_page) != head); bh = head = page_buffers(page); /* * If any blocks are being written to an encrypted file, encrypt them * into a bounce page. For simplicity, just encrypt until the last * block which might be needed. This may cause some unneeded blocks * (e.g. holes) to be unnecessarily encrypted, but this is rare and * can't happen in the common case of blocksize == PAGE_SIZE. */ if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) { gfp_t gfp_flags = GFP_NOFS; unsigned int enc_bytes = round_up(len, i_blocksize(inode)); /* * Since bounce page allocation uses a mempool, we can only use * a waiting mask (i.e. request guaranteed allocation) on the * first page of the bio. Otherwise it can deadlock. */ if (io->io_bio) gfp_flags = GFP_NOWAIT | __GFP_NOWARN; retry_encrypt: bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes, 0, gfp_flags); if (IS_ERR(bounce_page)) { ret = PTR_ERR(bounce_page); if (ret == -ENOMEM && (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) { gfp_t new_gfp_flags = GFP_NOFS; if (io->io_bio) ext4_io_submit(io); else new_gfp_flags |= __GFP_NOFAIL; memalloc_retry_wait(gfp_flags); gfp_flags = new_gfp_flags; goto retry_encrypt; } printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret); redirty_page_for_writepage(wbc, page); do { clear_buffer_async_write(bh); bh = bh->b_this_page; } while (bh != head); goto unlock; } } /* Now submit buffers to write */ do { if (!buffer_async_write(bh)) continue; io_submit_add_bh(io, inode, page, bounce_page, bh); nr_submitted++; clear_buffer_dirty(bh); } while ((bh = bh->b_this_page) != head); unlock: unlock_page(page); /* Nothing submitted - we have to end page writeback */ if (!nr_submitted) end_page_writeback(page); return ret; }