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Subject[PATCH v4 4/6] block: add zone append handling for direct I/O path
Date
For zoned block device, opt in for zone-append by setting
FMODE_ZONE_APPEND during open. Make direct IO submission path use
IOCB_ZONE_APPEND to send bio with append op. Make direct IO completion
return written-offset, in bytes, to upper layer via ret2 of
kiocb->ki_complete interface.
Write with the flag IOCB_ZONE_APPEND are ensured not be be short.
Prevent short write and instead return failure if appending write spans
beyond end of device.
Return failure if write is larger than max_append_limit and therefore
requires formation of multiple bios.

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Selvakumar S <selvakuma.s1@samsung.com>
Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Arnav Dawn <a.dawn@samsung.com>
Signed-off-by: Javier Gonzalez <javier.gonz@samsung.com>
---
fs/block_dev.c | 51 +++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 41 insertions(+), 10 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 47860e5..3b5836b 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -178,10 +178,19 @@ static struct inode *bdev_file_inode(struct file *file)
return file->f_mapping->host;
}

-static unsigned int dio_bio_write_op(struct kiocb *iocb)
+static unsigned int dio_bio_op(bool is_read, struct kiocb *iocb)
{
- unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
+ unsigned int op;

+ if (is_read)
+ return REQ_OP_READ;
+
+ if (iocb->ki_flags & IOCB_ZONE_APPEND)
+ op = REQ_OP_ZONE_APPEND;
+ else
+ op = REQ_OP_WRITE;
+
+ op |= REQ_SYNC | REQ_IDLE;
/* avoid the need for a I/O completion work item */
if (iocb->ki_flags & IOCB_DSYNC)
op |= REQ_FUA;
@@ -207,6 +216,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
loff_t pos = iocb->ki_pos;
bool should_dirty = false;
+ bool is_read = (iov_iter_rw(iter) == READ);
struct bio bio;
ssize_t ret;
blk_qc_t qc;
@@ -231,18 +241,17 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
bio.bi_private = current;
bio.bi_end_io = blkdev_bio_end_io_simple;
bio.bi_ioprio = iocb->ki_ioprio;
+ bio.bi_opf = dio_bio_op(is_read, iocb);

ret = bio_iov_iter_get_pages(&bio, iter);
if (unlikely(ret))
goto out;
ret = bio.bi_iter.bi_size;

- if (iov_iter_rw(iter) == READ) {
- bio.bi_opf = REQ_OP_READ;
+ if (is_read) {
if (iter_is_iovec(iter))
should_dirty = true;
} else {
- bio.bi_opf = dio_bio_write_op(iocb);
task_io_account_write(ret);
}
if (iocb->ki_flags & IOCB_HIPRI)
@@ -295,6 +304,14 @@ static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
}

+static inline long long blkdev_bio_ret2(struct kiocb *iocb, struct bio *bio)
+{
+ /* return written-offset for zone append in bytes */
+ if (op_is_write(bio_op(bio)) && iocb->ki_flags & IOCB_ZONE_APPEND)
+ return bio->bi_iter.bi_sector << SECTOR_SHIFT;
+ return 0;
+}
+
static void blkdev_bio_end_io(struct bio *bio)
{
struct blkdev_dio *dio = bio->bi_private;
@@ -307,15 +324,17 @@ static void blkdev_bio_end_io(struct bio *bio)
if (!dio->is_sync) {
struct kiocb *iocb = dio->iocb;
ssize_t ret;
+ long long ret2;

if (likely(!dio->bio.bi_status)) {
ret = dio->size;
iocb->ki_pos += ret;
+ ret2 = blkdev_bio_ret2(iocb, bio);
} else {
ret = blk_status_to_errno(dio->bio.bi_status);
}

- dio->iocb->ki_complete(iocb, ret, 0);
+ dio->iocb->ki_complete(iocb, ret, ret2);
if (dio->multi_bio)
bio_put(&dio->bio);
} else {
@@ -382,6 +401,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
bio->bi_private = dio;
bio->bi_end_io = blkdev_bio_end_io;
bio->bi_ioprio = iocb->ki_ioprio;
+ bio->bi_opf = dio_bio_op(is_read, iocb);

ret = bio_iov_iter_get_pages(bio, iter);
if (unlikely(ret)) {
@@ -391,11 +411,9 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
}

if (is_read) {
- bio->bi_opf = REQ_OP_READ;
if (dio->should_dirty)
bio_set_pages_dirty(bio);
} else {
- bio->bi_opf = dio_bio_write_op(iocb);
task_io_account_write(bio->bi_iter.bi_size);
}

@@ -419,6 +437,12 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
}

if (!dio->multi_bio) {
+ /* zone-append cannot work with multi bio*/
+ if (!is_read && iocb->ki_flags & IOCB_ZONE_APPEND) {
+ bio->bi_status = BLK_STS_IOERR;
+ bio_endio(bio);
+ break;
+ }
/*
* AIO needs an extra reference to ensure the dio
* structure which is embedded into the first bio
@@ -1841,6 +1865,7 @@ EXPORT_SYMBOL(blkdev_get_by_dev);
static int blkdev_open(struct inode * inode, struct file * filp)
{
struct block_device *bdev;
+ int ret;

/*
* Preserve backwards compatibility and allow large file access
@@ -1866,7 +1891,11 @@ static int blkdev_open(struct inode * inode, struct file * filp)
filp->f_mapping = bdev->bd_inode->i_mapping;
filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);

- return blkdev_get(bdev, filp->f_mode, filp);
+ ret = blkdev_get(bdev, filp->f_mode, filp);
+ if (blk_queue_is_zoned(bdev->bd_disk->queue))
+ filp->f_mode |= FMODE_ZONE_APPEND;
+
+ return ret;
}

static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
@@ -2017,7 +2046,9 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
return -EOPNOTSUPP;

- iov_iter_truncate(from, size - iocb->ki_pos);
+ if (iov_iter_truncate(from, size - iocb->ki_pos) &&
+ (iocb->ki_flags & IOCB_ZONE_APPEND))
+ return -ENOSPC;

blk_start_plug(&plug);
ret = __generic_file_write_iter(iocb, from);
--
2.7.4
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