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Date: Thu, 7 Nov 2013 12:26:30 +0100
From: Jan Kara <jack@...e.cz>
To: Kent Overstreet <kmo@...erainc.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-btrfs@...r.kernel.org, axboe@...nel.dk, hch@...radead.org,
Alexander Viro <viro@...iv.linux.org.uk>,
Chris Mason <chris.mason@...ionio.com>,
Jaegeuk Kim <jaegeuk.kim@...sung.com>,
Joern Engel <joern@...fs.org>,
Prasad Joshi <prasadjoshi.linux@...il.com>,
Trond Myklebust <Trond.Myklebust@...app.com>
Subject: Re: [PATCH 1/9] block: Convert various code to bio_for_each_segment()
On Mon 04-11-13 15:36:19, Kent Overstreet wrote:
> With immutable biovecs we don't want code accessing bi_io_vec directly -
> the uses this patch changes weren't incorrect since they all own the
> bio, but it makes the code harder to audit for no good reason - also,
> this will help with multipage bvecs later.
I think you've missed the code in fs/ext4/page-io.c in the conversion
(likely because it was added relatively recently).
Honza
>
> Signed-off-by: Kent Overstreet <kmo@...erainc.com>
> Cc: Jens Axboe <axboe@...nel.dk>
> Cc: Alexander Viro <viro@...iv.linux.org.uk>
> Cc: Chris Mason <chris.mason@...ionio.com>
> Cc: Jaegeuk Kim <jaegeuk.kim@...sung.com>
> Cc: Joern Engel <joern@...fs.org>
> Cc: Prasad Joshi <prasadjoshi.linux@...il.com>
> Cc: Trond Myklebust <Trond.Myklebust@...app.com>
> ---
> fs/btrfs/compression.c | 10 ++++------
> fs/btrfs/disk-io.c | 11 ++++-------
> fs/btrfs/extent_io.c | 37 ++++++++++++++-----------------------
> fs/btrfs/inode.c | 15 ++++++---------
> fs/f2fs/data.c | 13 +++++--------
> fs/f2fs/segment.c | 12 +++++-------
> fs/logfs/dev_bdev.c | 18 +++++++-----------
> fs/mpage.c | 17 ++++++++---------
> fs/nfs/blocklayout/blocklayout.c | 34 +++++++++++++---------------------
> 9 files changed, 66 insertions(+), 101 deletions(-)
>
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index 06ab821..52e7848 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -203,18 +203,16 @@ csum_failed:
> if (cb->errors) {
> bio_io_error(cb->orig_bio);
> } else {
> - int bio_index = 0;
> - struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
> + int i;
> + struct bio_vec *bvec;
>
> /*
> * we have verified the checksum already, set page
> * checked so the end_io handlers know about it
> */
> - while (bio_index < cb->orig_bio->bi_vcnt) {
> + bio_for_each_segment_all(bvec, cb->orig_bio, i)
> SetPageChecked(bvec->bv_page);
> - bvec++;
> - bio_index++;
> - }
> +
> bio_endio(cb->orig_bio, 0);
> }
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 62176ad..733182e 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -850,20 +850,17 @@ int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
>
> static int btree_csum_one_bio(struct bio *bio)
> {
> - struct bio_vec *bvec = bio->bi_io_vec;
> - int bio_index = 0;
> + struct bio_vec *bvec;
> struct btrfs_root *root;
> - int ret = 0;
> + int i, ret = 0;
>
> - WARN_ON(bio->bi_vcnt <= 0);
> - while (bio_index < bio->bi_vcnt) {
> + bio_for_each_segment_all(bvec, bio, i) {
> root = BTRFS_I(bvec->bv_page->mapping->host)->root;
> ret = csum_dirty_buffer(root, bvec->bv_page);
> if (ret)
> break;
> - bio_index++;
> - bvec++;
> }
> +
> return ret;
> }
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 0df176a..ea5a08b 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2014,7 +2014,7 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
> }
> bio->bi_bdev = dev->bdev;
> bio_add_page(bio, page, length, start - page_offset(page));
> - btrfsic_submit_bio(WRITE_SYNC, bio);
> + btrfsic_submit_bio(WRITE_SYNC, bio); /* XXX: submit_bio_wait() */
> wait_for_completion(&compl);
>
> if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
> @@ -2340,12 +2340,13 @@ int end_extent_writepage(struct page *page, int err, u64 start, u64 end)
> */
> static void end_bio_extent_writepage(struct bio *bio, int err)
> {
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> + struct bio_vec *bvec;
> struct extent_io_tree *tree;
> u64 start;
> u64 end;
> + int i;
>
> - do {
> + bio_for_each_segment_all(bvec, bio, i) {
> struct page *page = bvec->bv_page;
> tree = &BTRFS_I(page->mapping->host)->io_tree;
>
> @@ -2363,14 +2364,11 @@ static void end_bio_extent_writepage(struct bio *bio, int err)
> start = page_offset(page);
> end = start + bvec->bv_offset + bvec->bv_len - 1;
>
> - if (--bvec >= bio->bi_io_vec)
> - prefetchw(&bvec->bv_page->flags);
> -
> if (end_extent_writepage(page, err, start, end))
> continue;
>
> end_page_writeback(page);
> - } while (bvec >= bio->bi_io_vec);
> + }
>
> bio_put(bio);
> }
> @@ -2400,9 +2398,8 @@ endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
> */
> static void end_bio_extent_readpage(struct bio *bio, int err)
> {
> + struct bio_vec *bvec;
> int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> - struct bio_vec *bvec_end = bio->bi_io_vec + bio->bi_vcnt - 1;
> - struct bio_vec *bvec = bio->bi_io_vec;
> struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
> struct extent_io_tree *tree;
> u64 offset = 0;
> @@ -2413,11 +2410,12 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
> u64 extent_len = 0;
> int mirror;
> int ret;
> + int i;
>
> if (err)
> uptodate = 0;
>
> - do {
> + bio_for_each_segment_all(bvec, bio, i) {
> struct page *page = bvec->bv_page;
> struct inode *inode = page->mapping->host;
>
> @@ -2441,9 +2439,6 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
> end = start + bvec->bv_offset + bvec->bv_len - 1;
> len = bvec->bv_len;
>
> - if (++bvec <= bvec_end)
> - prefetchw(&bvec->bv_page->flags);
> -
> mirror = io_bio->mirror_num;
> if (likely(uptodate && tree->ops &&
> tree->ops->readpage_end_io_hook)) {
> @@ -2524,7 +2519,7 @@ readpage_ok:
> extent_start = start;
> extent_len = end + 1 - start;
> }
> - } while (bvec <= bvec_end);
> + }
>
> if (extent_len)
> endio_readpage_release_extent(tree, extent_start, extent_len,
> @@ -2555,7 +2550,6 @@ btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
> }
>
> if (bio) {
> - bio->bi_iter.bi_size = 0;
> bio->bi_bdev = bdev;
> bio->bi_iter.bi_sector = first_sector;
> btrfs_bio = btrfs_io_bio(bio);
> @@ -3418,20 +3412,18 @@ static void end_extent_buffer_writeback(struct extent_buffer *eb)
>
> static void end_bio_extent_buffer_writepage(struct bio *bio, int err)
> {
> - int uptodate = err == 0;
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> + struct bio_vec *bvec;
> struct extent_buffer *eb;
> - int done;
> + int i, done;
>
> - do {
> + bio_for_each_segment_all(bvec, bio, i) {
> struct page *page = bvec->bv_page;
>
> - bvec--;
> eb = (struct extent_buffer *)page->private;
> BUG_ON(!eb);
> done = atomic_dec_and_test(&eb->io_pages);
>
> - if (!uptodate || test_bit(EXTENT_BUFFER_IOERR, &eb->bflags)) {
> + if (err || test_bit(EXTENT_BUFFER_IOERR, &eb->bflags)) {
> set_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
> ClearPageUptodate(page);
> SetPageError(page);
> @@ -3443,10 +3435,9 @@ static void end_bio_extent_buffer_writepage(struct bio *bio, int err)
> continue;
>
> end_extent_buffer_writeback(eb);
> - } while (bvec >= bio->bi_io_vec);
> + }
>
> bio_put(bio);
> -
> }
>
> static int write_one_eb(struct extent_buffer *eb,
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 6f5a64d..b7209a6 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -6765,17 +6765,16 @@ unlock_err:
> static void btrfs_endio_direct_read(struct bio *bio, int err)
> {
> struct btrfs_dio_private *dip = bio->bi_private;
> - struct bio_vec *bvec_end = bio->bi_io_vec + bio->bi_vcnt - 1;
> - struct bio_vec *bvec = bio->bi_io_vec;
> + struct bio_vec *bvec;
> struct inode *inode = dip->inode;
> struct btrfs_root *root = BTRFS_I(inode)->root;
> struct bio *dio_bio;
> u32 *csums = (u32 *)dip->csum;
> - int index = 0;
> u64 start;
> + int i;
>
> start = dip->logical_offset;
> - do {
> + bio_for_each_segment_all(bvec, bio, i) {
> if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
> struct page *page = bvec->bv_page;
> char *kaddr;
> @@ -6791,18 +6790,16 @@ static void btrfs_endio_direct_read(struct bio *bio, int err)
> local_irq_restore(flags);
>
> flush_dcache_page(bvec->bv_page);
> - if (csum != csums[index]) {
> + if (csum != csums[i]) {
> btrfs_err(root->fs_info, "csum failed ino %llu off %llu csum %u expected csum %u",
> btrfs_ino(inode), start, csum,
> - csums[index]);
> + csums[i]);
> err = -EIO;
> }
> }
>
> start += bvec->bv_len;
> - bvec++;
> - index++;
> - } while (bvec <= bvec_end);
> + }
>
> unlock_extent(&BTRFS_I(inode)->io_tree, dip->logical_offset,
> dip->logical_offset + dip->bytes - 1);
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 97d8b34..dd02271 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -357,23 +357,20 @@ repeat:
>
> static void read_end_io(struct bio *bio, int err)
> {
> - const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> + struct bio_vec *bvec;
> + int i;
>
> - do {
> + bio_for_each_segment_all(bvec, bio, i) {
> struct page *page = bvec->bv_page;
>
> - if (--bvec >= bio->bi_io_vec)
> - prefetchw(&bvec->bv_page->flags);
> -
> - if (uptodate) {
> + if (!err) {
> SetPageUptodate(page);
> } else {
> ClearPageUptodate(page);
> SetPageError(page);
> }
> unlock_page(page);
> - } while (bvec >= bio->bi_io_vec);
> + }
> bio_put(bio);
> }
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 9d77ce1..4382c90 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -575,16 +575,14 @@ static const struct segment_allocation default_salloc_ops = {
>
> static void f2fs_end_io_write(struct bio *bio, int err)
> {
> - const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> struct bio_private *p = bio->bi_private;
> + struct bio_vec *bvec;
> + int i;
>
> - do {
> + bio_for_each_segment_all(bvec, bio, i) {
> struct page *page = bvec->bv_page;
>
> - if (--bvec >= bio->bi_io_vec)
> - prefetchw(&bvec->bv_page->flags);
> - if (!uptodate) {
> + if (err) {
> SetPageError(page);
> if (page->mapping)
> set_bit(AS_EIO, &page->mapping->flags);
> @@ -593,7 +591,7 @@ static void f2fs_end_io_write(struct bio *bio, int err)
> }
> end_page_writeback(page);
> dec_page_count(p->sbi, F2FS_WRITEBACK);
> - } while (bvec >= bio->bi_io_vec);
> + }
>
> if (p->is_sync)
> complete(p->wait);
> diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
> index a1b161f..ca42715 100644
> --- a/fs/logfs/dev_bdev.c
> +++ b/fs/logfs/dev_bdev.c
> @@ -67,22 +67,18 @@ static DECLARE_WAIT_QUEUE_HEAD(wq);
> static void writeseg_end_io(struct bio *bio, int err)
> {
> const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> + struct bio_vec *bvec;
> + int i;
> struct super_block *sb = bio->bi_private;
> struct logfs_super *super = logfs_super(sb);
> - struct page *page;
>
> BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
> BUG_ON(err);
> - BUG_ON(bio->bi_vcnt == 0);
> - do {
> - page = bvec->bv_page;
> - if (--bvec >= bio->bi_io_vec)
> - prefetchw(&bvec->bv_page->flags);
> -
> - end_page_writeback(page);
> - page_cache_release(page);
> - } while (bvec >= bio->bi_io_vec);
> +
> + bio_for_each_segment_all(bvec, bio, i) {
> + end_page_writeback(bvec->bv_page);
> + page_cache_release(bvec->bv_page);
> + }
> bio_put(bio);
> if (atomic_dec_and_test(&super->s_pending_writes))
> wake_up(&wq);
> diff --git a/fs/mpage.c b/fs/mpage.c
> index 92b125f..4979ffa 100644
> --- a/fs/mpage.c
> +++ b/fs/mpage.c
> @@ -43,16 +43,14 @@
> */
> static void mpage_end_io(struct bio *bio, int err)
> {
> - const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> + struct bio_vec *bv;
> + int i;
>
> - do {
> - struct page *page = bvec->bv_page;
> + bio_for_each_segment_all(bv, bio, i) {
> + struct page *page = bv->bv_page;
>
> - if (--bvec >= bio->bi_io_vec)
> - prefetchw(&bvec->bv_page->flags);
> if (bio_data_dir(bio) == READ) {
> - if (uptodate) {
> + if (!err) {
> SetPageUptodate(page);
> } else {
> ClearPageUptodate(page);
> @@ -60,14 +58,15 @@ static void mpage_end_io(struct bio *bio, int err)
> }
> unlock_page(page);
> } else { /* bio_data_dir(bio) == WRITE */
> - if (!uptodate) {
> + if (err) {
> SetPageError(page);
> if (page->mapping)
> set_bit(AS_EIO, &page->mapping->flags);
> }
> end_page_writeback(page);
> }
> - } while (bvec >= bio->bi_io_vec);
> + }
> +
> bio_put(bio);
> }
>
> diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
> index af73896..56ff823 100644
> --- a/fs/nfs/blocklayout/blocklayout.c
> +++ b/fs/nfs/blocklayout/blocklayout.c
> @@ -202,18 +202,14 @@ static struct bio *bl_add_page_to_bio(struct bio *bio, int npg, int rw,
> static void bl_end_io_read(struct bio *bio, int err)
> {
> struct parallel_io *par = bio->bi_private;
> - const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> + struct bio_vec *bvec;
> + int i;
>
> - do {
> - struct page *page = bvec->bv_page;
> + if (!err)
> + bio_for_each_segment_all(bvec, bio, i)
> + SetPageUptodate(bvec->bv_page);
>
> - if (--bvec >= bio->bi_io_vec)
> - prefetchw(&bvec->bv_page->flags);
> - if (uptodate)
> - SetPageUptodate(page);
> - } while (bvec >= bio->bi_io_vec);
> - if (!uptodate) {
> + if (err) {
> struct nfs_read_data *rdata = par->data;
> struct nfs_pgio_header *header = rdata->header;
>
> @@ -384,20 +380,16 @@ static void mark_extents_written(struct pnfs_block_layout *bl,
> static void bl_end_io_write_zero(struct bio *bio, int err)
> {
> struct parallel_io *par = bio->bi_private;
> - const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> -
> - do {
> - struct page *page = bvec->bv_page;
> + struct bio_vec *bvec;
> + int i;
>
> - if (--bvec >= bio->bi_io_vec)
> - prefetchw(&bvec->bv_page->flags);
> + bio_for_each_segment_all(bvec, bio, i) {
> /* This is the zeroing page we added */
> - end_page_writeback(page);
> - page_cache_release(page);
> - } while (bvec >= bio->bi_io_vec);
> + end_page_writeback(bvec->bv_page);
> + page_cache_release(bvec->bv_page);
> + }
>
> - if (unlikely(!uptodate)) {
> + if (unlikely(err)) {
> struct nfs_write_data *data = par->data;
> struct nfs_pgio_header *header = data->header;
>
> --
> 1.8.4.rc3
>
> --
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--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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