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authorJohannes Thumshirn <johannes.thumshirn@wdc.com>2020-02-14 00:24:33 +0900
committerDavid Sterba <dsterba@suse.com>2020-03-23 17:01:39 +0100
commit314b6dd0eebfa99621202f2be0b5f76e01d849e1 (patch)
treef2a2b82cb7c571224fe2ed14fff7e986b794b5b8
parent8f32380d3f2904ad0e98574ae17f2018f6dd277e (diff)
btrfs: use bios instead of buffer_heads from super block writeout
Similar to the superblock read path, change the write path to using bios and pages instead of buffer_heads. This allows us to skip over the buffer_head code, for writing the superblock to disk. This is based on a patch originally authored by Nikolay Borisov. Co-developed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/disk-io.c127
1 files changed, 73 insertions, 54 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index ac9554d71a46..756bf2ab64cd 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -7,7 +7,6 @@
#include <linux/blkdev.h>
#include <linux/radix-tree.h>
#include <linux/writeback.h>
-#include <linux/buffer_head.h>
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include <linux/slab.h>
@@ -3395,25 +3394,34 @@ fail:
}
ALLOW_ERROR_INJECTION(open_ctree, ERRNO);
-static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
+static void btrfs_end_super_write(struct bio *bio)
{
- if (uptodate) {
- set_buffer_uptodate(bh);
- } else {
- struct btrfs_device *device = (struct btrfs_device *)
- bh->b_private;
-
- btrfs_warn_rl_in_rcu(device->fs_info,
- "lost page write due to IO error on %s",
- rcu_str_deref(device->name));
- /* note, we don't set_buffer_write_io_error because we have
- * our own ways of dealing with the IO errors
- */
- clear_buffer_uptodate(bh);
- btrfs_dev_stat_inc_and_print(device, BTRFS_DEV_STAT_WRITE_ERRS);
+ struct btrfs_device *device = bio->bi_private;
+ struct bio_vec *bvec;
+ struct bvec_iter_all iter_all;
+ struct page *page;
+
+ bio_for_each_segment_all(bvec, bio, iter_all) {
+ page = bvec->bv_page;
+
+ if (bio->bi_status) {
+ btrfs_warn_rl_in_rcu(device->fs_info,
+ "lost page write due to IO error on %s (%d)",
+ rcu_str_deref(device->name),
+ blk_status_to_errno(bio->bi_status));
+ ClearPageUptodate(page);
+ SetPageError(page);
+ btrfs_dev_stat_inc_and_print(device,
+ BTRFS_DEV_STAT_WRITE_ERRS);
+ } else {
+ SetPageUptodate(page);
+ }
+
+ put_page(page);
+ unlock_page(page);
}
- unlock_buffer(bh);
- put_bh(bh);
+
+ bio_put(bio);
}
struct btrfs_super_block *btrfs_read_dev_one_super(struct block_device *bdev,
@@ -3473,25 +3481,23 @@ struct btrfs_super_block *btrfs_read_dev_super(struct block_device *bdev)
/*
* Write superblock @sb to the @device. Do not wait for completion, all the
- * buffer heads we write are pinned.
+ * pages we use for writing are locked.
*
* Write @max_mirrors copies of the superblock, where 0 means default that fit
* the expected device size at commit time. Note that max_mirrors must be
* same for write and wait phases.
*
- * Return number of errors when buffer head is not found or submission fails.
+ * Return number of errors when page is not found or submission fails.
*/
static int write_dev_supers(struct btrfs_device *device,
struct btrfs_super_block *sb, int max_mirrors)
{
struct btrfs_fs_info *fs_info = device->fs_info;
+ struct address_space *mapping = device->bdev->bd_inode->i_mapping;
SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
- struct buffer_head *bh;
int i;
- int ret;
int errors = 0;
u64 bytenr;
- int op_flags;
if (max_mirrors == 0)
max_mirrors = BTRFS_SUPER_MIRROR_MAX;
@@ -3499,6 +3505,10 @@ static int write_dev_supers(struct btrfs_device *device,
shash->tfm = fs_info->csum_shash;
for (i = 0; i < max_mirrors; i++) {
+ struct page *page;
+ struct bio *bio;
+ struct btrfs_super_block *disk_super;
+
bytenr = btrfs_sb_offset(i);
if (bytenr + BTRFS_SUPER_INFO_SIZE >=
device->commit_total_bytes)
@@ -3511,37 +3521,45 @@ static int write_dev_supers(struct btrfs_device *device,
BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
crypto_shash_final(shash, sb->csum);
- /* One reference for us, and we leave it for the caller */
- bh = __getblk(device->bdev, bytenr / BTRFS_BDEV_BLOCKSIZE,
- BTRFS_SUPER_INFO_SIZE);
- if (!bh) {
+ page = find_or_create_page(mapping, bytenr >> PAGE_SHIFT,
+ GFP_NOFS);
+ if (!page) {
btrfs_err(device->fs_info,
- "couldn't get super buffer head for bytenr %llu",
+ "couldn't get super block page for bytenr %llu",
bytenr);
errors++;
continue;
}
- memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
+ /* Bump the refcount for wait_dev_supers() */
+ get_page(page);
- /* one reference for submit_bh */
- get_bh(bh);
+ disk_super = page_address(page);
+ memcpy(disk_super, sb, BTRFS_SUPER_INFO_SIZE);
- set_buffer_uptodate(bh);
- lock_buffer(bh);
- bh->b_end_io = btrfs_end_buffer_write_sync;
- bh->b_private = device;
+ /*
+ * Directly use bios here instead of relying on the page cache
+ * to do I/O, so we don't lose the ability to do integrity
+ * checking.
+ */
+ bio = bio_alloc(GFP_NOFS, 1);
+ bio_set_dev(bio, device->bdev);
+ bio->bi_iter.bi_sector = bytenr >> SECTOR_SHIFT;
+ bio->bi_private = device;
+ bio->bi_end_io = btrfs_end_super_write;
+ __bio_add_page(bio, page, BTRFS_SUPER_INFO_SIZE,
+ offset_in_page(bytenr));
/*
- * we fua the first super. The others we allow
- * to go down lazy.
+ * We FUA only the first super block. The others we allow to
+ * go down lazy and there's a short window where the on-disk
+ * copies might still contain the older version.
*/
- op_flags = REQ_SYNC | REQ_META | REQ_PRIO;
+ bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_META | REQ_PRIO;
if (i == 0 && !btrfs_test_opt(device->fs_info, NOBARRIER))
- op_flags |= REQ_FUA;
- ret = btrfsic_submit_bh(REQ_OP_WRITE, op_flags, bh);
- if (ret)
- errors++;
+ bio->bi_opf |= REQ_FUA;
+
+ btrfsic_submit_bio(bio);
}
return errors < i ? 0 : -1;
}
@@ -3550,12 +3568,11 @@ static int write_dev_supers(struct btrfs_device *device,
* Wait for write completion of superblocks done by write_dev_supers,
* @max_mirrors same for write and wait phases.
*
- * Return number of errors when buffer head is not found or not marked up to
+ * Return number of errors when page is not found or not marked up to
* date.
*/
static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)
{
- struct buffer_head *bh;
int i;
int errors = 0;
bool primary_failed = false;
@@ -3565,32 +3582,34 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)
max_mirrors = BTRFS_SUPER_MIRROR_MAX;
for (i = 0; i < max_mirrors; i++) {
+ struct page *page;
+
bytenr = btrfs_sb_offset(i);
if (bytenr + BTRFS_SUPER_INFO_SIZE >=
device->commit_total_bytes)
break;
- bh = __find_get_block(device->bdev,
- bytenr / BTRFS_BDEV_BLOCKSIZE,
- BTRFS_SUPER_INFO_SIZE);
- if (!bh) {
+ page = find_get_page(device->bdev->bd_inode->i_mapping,
+ bytenr >> PAGE_SHIFT);
+ if (!page) {
errors++;
if (i == 0)
primary_failed = true;
continue;
}
- wait_on_buffer(bh);
- if (!buffer_uptodate(bh)) {
+ /* Page is submitted locked and unlocked once the IO completes */
+ wait_on_page_locked(page);
+ if (PageError(page)) {
errors++;
if (i == 0)
primary_failed = true;
}
- /* drop our reference */
- brelse(bh);
+ /* Drop our reference */
+ put_page(page);
- /* drop the reference from the writing run */
- brelse(bh);
+ /* Drop the reference from the writing run */
+ put_page(page);
}
/* log error, force error return */