v4.19.13 snapshot.
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
new file mode 100644
index 0000000..db75901
--- /dev/null
+++ b/fs/ext4/page-io.c
@@ -0,0 +1,537 @@
+// 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/backing-dev.h>
+
+#include "ext4_jbd2.h"
+#include "xattr.h"
+#include "acl.h"
+
+static struct kmem_cache *io_end_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;
+ return 0;
+}
+
+void ext4_exit_pageio(void)
+{
+ kmem_cache_destroy(io_end_cachep);
+}
+
+/*
+ * 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)
+{
+ int i;
+ struct bio_vec *bvec;
+
+ bio_for_each_segment_all(bvec, bio, i) {
+ struct page *page = bvec->bv_page;
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ struct page *data_page = NULL;
+#endif
+ 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 (!page)
+ continue;
+
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ if (!page->mapping) {
+ /* The bounce data pages are unmapped. */
+ data_page = page;
+ fscrypt_pullback_bio_page(&page, false);
+ }
+#endif
+
+ 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 BH_Uptodate_Lock
+ * to avoid races with other end io clearing async_write flags
+ */
+ local_irq_save(flags);
+ bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
+ 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)
+ buffer_io_error(bh);
+ } while ((bh = bh->b_this_page) != head);
+ bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
+ local_irq_restore(flags);
+ if (!under_io) {
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ if (data_page)
+ fscrypt_restore_control_page(data_page);
+#endif
+ 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);
+ }
+ 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(ext4_io_end_t *io)
+{
+ struct inode *inode = io->inode;
+ loff_t offset = io->offset;
+ ssize_t size = io->size;
+ handle_t *handle = io->handle;
+ int ret = 0;
+
+ ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
+ "list->prev 0x%p\n",
+ io, inode->i_ino, io->list.next, io->list.prev);
+
+ io->handle = NULL; /* Following call will use up the handle */
+ ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
+ 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, offset %llu, size %zd, error %d)",
+ inode->i_ino, offset, size, ret);
+ }
+ ext4_clear_io_unwritten_flag(io);
+ ext4_release_io_end(io);
+ 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, *io0, *io1;
+
+ if (list_empty(head))
+ return;
+
+ ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
+ list_for_each_entry(io, head, list) {
+ cur = &io->list;
+ before = cur->prev;
+ io0 = container_of(before, ext4_io_end_t, list);
+ after = cur->next;
+ io1 = container_of(after, ext4_io_end_t, list);
+
+ ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
+ io, inode->i_ino, io0, io1);
+ }
+#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;
+ 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 = list_entry(unwritten.next, ext4_io_end_t, list);
+ BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
+ list_del_init(&io->list);
+
+ err = ext4_end_io(io);
+ 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 = kmem_cache_zalloc(io_end_cachep, flags);
+ if (io) {
+ io->inode = inode;
+ INIT_LIST_HEAD(&io->list);
+ atomic_set(&io->count, 1);
+ }
+ return io;
+}
+
+void ext4_put_io_end_defer(ext4_io_end_t *io_end)
+{
+ if (atomic_dec_and_test(&io_end->count)) {
+ if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
+ 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 (atomic_dec_and_test(&io_end->count)) {
+ if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
+ err = ext4_convert_unwritten_extents(io_end->handle,
+ io_end->inode, io_end->offset,
+ io_end->size);
+ 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)
+{
+ atomic_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;
+ char b[BDEVNAME_SIZE];
+
+ if (WARN_ONCE(!io_end, "io_end is NULL: %s: sector %Lu len %u err %d\n",
+ bio_devname(bio, b),
+ (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 "
+ "(offset %llu size %ld starting block %llu)",
+ bio->bi_status, inode->i_ino,
+ (unsigned long long) io_end->offset,
+ (long) io_end->size,
+ (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) {
+ int io_op_flags = io->io_wbc->sync_mode == WB_SYNC_ALL ?
+ REQ_SYNC : 0;
+ io->io_bio->bi_write_hint = io->io_end->inode->i_write_hint;
+ bio_set_op_attrs(io->io_bio, REQ_OP_WRITE, io_op_flags);
+ 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 int io_submit_init_bio(struct ext4_io_submit *io,
+ struct buffer_head *bh)
+{
+ struct bio *bio;
+
+ bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
+ if (!bio)
+ return -ENOMEM;
+ wbc_init_bio(io->io_wbc, bio);
+ bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+ bio_set_dev(bio, bh->b_bdev);
+ 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;
+ return 0;
+}
+
+static int io_submit_add_bh(struct ext4_io_submit *io,
+ struct inode *inode,
+ struct page *page,
+ struct buffer_head *bh)
+{
+ int ret;
+
+ if (io->io_bio && bh->b_blocknr != io->io_next_block) {
+submit_and_retry:
+ ext4_io_submit(io);
+ }
+ if (io->io_bio == NULL) {
+ ret = io_submit_init_bio(io, bh);
+ if (ret)
+ return ret;
+ io->io_bio->bi_write_hint = inode->i_write_hint;
+ }
+ ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
+ if (ret != bh->b_size)
+ goto submit_and_retry;
+ wbc_account_io(io->io_wbc, page, bh->b_size);
+ io->io_next_block++;
+ return 0;
+}
+
+int ext4_bio_write_page(struct ext4_io_submit *io,
+ struct page *page,
+ int len,
+ struct writeback_control *wbc,
+ bool keep_towrite)
+{
+ struct page *data_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;
+
+ 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_bio_end_io() 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);
+ clean_bdev_bh_alias(bh);
+ }
+ set_buffer_async_write(bh);
+ nr_to_submit++;
+ } while ((bh = bh->b_this_page) != head);
+
+ bh = head = page_buffers(page);
+
+ if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
+ nr_to_submit) {
+ gfp_t gfp_flags = GFP_NOFS;
+
+ retry_encrypt:
+ data_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
+ page->index, gfp_flags);
+ if (IS_ERR(data_page)) {
+ ret = PTR_ERR(data_page);
+ if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
+ if (io->io_bio) {
+ ext4_io_submit(io);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
+ }
+ gfp_flags |= __GFP_NOFAIL;
+ goto retry_encrypt;
+ }
+ data_page = NULL;
+ goto out;
+ }
+ }
+
+ /* Now submit buffers to write */
+ do {
+ if (!buffer_async_write(bh))
+ continue;
+ ret = io_submit_add_bh(io, inode,
+ data_page ? data_page : page, bh);
+ if (ret) {
+ /*
+ * We only get here on ENOMEM. Not much else
+ * we can do but mark the page as dirty, and
+ * better luck next time.
+ */
+ break;
+ }
+ nr_submitted++;
+ clear_buffer_dirty(bh);
+ } while ((bh = bh->b_this_page) != head);
+
+ /* Error stopped previous loop? Clean up buffers... */
+ if (ret) {
+ out:
+ if (data_page)
+ fscrypt_restore_control_page(data_page);
+ 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);
+ }
+ unlock_page(page);
+ /* Nothing submitted - we have to end page writeback */
+ if (!nr_submitted)
+ end_page_writeback(page);
+ return ret;
+}