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btrfs: switch to iomap for direct IO

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We're using direct io implementation based on buffer heads. This patch
switches to the new iomap infrastructure.

Switch from __blockdev_direct_IO() to iomap_dio_rw().  Rename
btrfs_get_blocks_direct() to btrfs_dio_iomap_begin() and use it as
iomap_begin() for iomap direct I/O functions. This function allocates
and locks all the blocks required for the I/O.  btrfs_submit_direct() is
used as the submit_io() hook for direct I/O ops.

Since we need direct I/O reads to go through iomap_dio_rw(), we change
file_operations.read_iter() to a btrfs_file_read_iter() which calls
btrfs_direct_IO() for direct reads and falls back to
generic_file_buffered_read() for incomplete reads and buffered reads.

We don't need address_space.direct_IO() anymore: set it to noop.

Similarly, we don't need flags used in __blockdev_direct_IO(). iomap is
capable of direct I/O reads from a hole, so we don't need to return
-ENOENT.

Btrfs direct I/O is now done under i_rwsem, shared in case of reads and
exclusive in case of writes. This guards against simultaneous truncates.

Use iomap->iomap_end() to check for failed or incomplete direct I/O:

  - for writes, call __endio_write_update_ordered()
  - for reads, unlock extents

btrfs_dio_data is now hooked in iomap->private and not
current->journal_info. It carries the reservation variable and the
amount of data submitted, so we can calculate the amount of data to call
__endio_write_update_ordered in case of an error.

This patch removes last use of struct buffer_head from btrfs.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues 2020-08-17 11:18:21 -05:00 committed by David Sterba
parent 154f7cb868
commit f85781fb50
4 changed files with 176 additions and 172 deletions
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1
fs/btrfs/Kconfig
View File

@ -14,6 +14,7 @@ config BTRFS_FS
select LZO_DECOMPRESS
select ZSTD_COMPRESS
select ZSTD_DECOMPRESS
select FS_IOMAP
select RAID6_PQ
select XOR_BLOCKS
select SRCU

1
fs/btrfs/ctree.h
View File

@ -3020,6 +3020,7 @@ int btrfs_writepage_cow_fixup(struct page *page, u64 start, u64 end);
void btrfs_writepage_endio_finish_ordered(struct page *page, u64 start,
u64 end, int uptodate);
extern const struct dentry_operations btrfs_dentry_operations;
ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
/* ioctl.c */
long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);

21
fs/btrfs/file.c
View File

@ -1870,7 +1870,7 @@ static ssize_t __btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
loff_t endbyte;
int err;
written = generic_file_direct_write(iocb, from);
written = btrfs_direct_IO(iocb, from);
if (written < 0 || !iov_iter_count(from))
return written;
@ -3568,9 +3568,26 @@ static int btrfs_file_open(struct inode *inode, struct file *filp)
return generic_file_open(inode, filp);
}
static ssize_t btrfs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
ssize_t ret = 0;
if (iocb->ki_flags & IOCB_DIRECT) {
struct inode *inode = file_inode(iocb->ki_filp);
inode_lock_shared(inode);
ret = btrfs_direct_IO(iocb, to);
inode_unlock_shared(inode);
if (ret < 0)
return ret;
}
return generic_file_buffered_read(iocb, to, ret);
}
const struct file_operations btrfs_file_operations = {
.llseek = btrfs_file_llseek,
.read_iter = generic_file_read_iter,
.read_iter = btrfs_file_read_iter,
.splice_read = generic_file_splice_read,
.write_iter = btrfs_file_write_iter,
.splice_write = iter_file_splice_write,

325
fs/btrfs/inode.c
View File

@ -6,7 +6,6 @@
#include <crypto/hash.h>
#include <linux/kernel.h>
#include <linux/bio.h>
#include <linux/buffer_head.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
@ -31,6 +30,7 @@
#include <linux/swap.h>
#include <linux/migrate.h>
#include <linux/sched/mm.h>
#include <linux/iomap.h>
#include <asm/unaligned.h>
#include "misc.h"
#include "ctree.h"
@ -59,9 +59,9 @@ struct btrfs_iget_args {
struct btrfs_dio_data {
u64 reserve;
u64 unsubmitted_oe_range_start;
u64 unsubmitted_oe_range_end;
int overwrite;
loff_t length;
ssize_t submitted;
struct extent_changeset *data_reserved;
};
static const struct inode_operations btrfs_dir_inode_operations;
@ -7103,7 +7103,7 @@ out:
}
static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
struct extent_state **cached_state, int writing)
struct extent_state **cached_state, bool writing)
{
struct btrfs_ordered_extent *ordered;
int ret = 0;
@ -7241,30 +7241,7 @@ static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
}
static int btrfs_get_blocks_direct_read(struct extent_map *em,
struct buffer_head *bh_result,
struct inode *inode,
u64 start, u64 len)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
if (em->block_start == EXTENT_MAP_HOLE ||
test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
return -ENOENT;
len = min(len, em->len - (start - em->start));
bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
inode->i_blkbits;
bh_result->b_size = len;
bh_result->b_bdev = fs_info->fs_devices->latest_bdev;
set_buffer_mapped(bh_result);
return 0;
}
static int btrfs_get_blocks_direct_write(struct extent_map **map,
struct buffer_head *bh_result,
struct inode *inode,
struct btrfs_dio_data *dio_data,
u64 start, u64 len)
@ -7325,7 +7302,6 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
}
/* this will cow the extent */
len = bh_result->b_size;
free_extent_map(em);
*map = em = btrfs_new_extent_direct(BTRFS_I(inode), start, len);
if (IS_ERR(em)) {
@ -7336,64 +7312,76 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
len = min(len, em->len - (start - em->start));
skip_cow:
bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
inode->i_blkbits;
bh_result->b_size = len;
bh_result->b_bdev = fs_info->fs_devices->latest_bdev;
set_buffer_mapped(bh_result);
if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
set_buffer_new(bh_result);
/*
* Need to update the i_size under the extent lock so buffered
* readers will get the updated i_size when we unlock.
*/
if (!dio_data->overwrite && start + len > i_size_read(inode))
if (start + len > i_size_read(inode))
i_size_write(inode, start + len);
WARN_ON(dio_data->reserve < len);
dio_data->reserve -= len;
dio_data->unsubmitted_oe_range_end = start + len;
current->journal_info = dio_data;
out:
return ret;
}
static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
loff_t length, unsigned int flags, struct iomap *iomap,
struct iomap *srcmap)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct extent_map *em;
struct extent_state *cached_state = NULL;
struct btrfs_dio_data *dio_data = NULL;
u64 start = iblock << inode->i_blkbits;
u64 lockstart, lockend;
u64 len = bh_result->b_size;
const bool write = !!(flags & IOMAP_WRITE);
int ret = 0;
u64 len = length;
bool unlock_extents = false;
if (!create)
if (!write)
len = min_t(u64, len, fs_info->sectorsize);
lockstart = start;
lockend = start + len - 1;
if (current->journal_info) {
/*
* Need to pull our outstanding extents and set journal_info to NULL so
* that anything that needs to check if there's a transaction doesn't get
* confused.
*/
dio_data = current->journal_info;
current->journal_info = NULL;
/*
* The generic stuff only does filemap_write_and_wait_range, which
* isn't enough if we've written compressed pages to this area, so we
* need to flush the dirty pages again to make absolutely sure that any
* outstanding dirty pages are on disk.
*/
if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
&BTRFS_I(inode)->runtime_flags)) {
ret = filemap_fdatawrite_range(inode->i_mapping, start,
start + length - 1);
if (ret)
return ret;
}
dio_data = kzalloc(sizeof(*dio_data), GFP_NOFS);
if (!dio_data)
return -ENOMEM;
dio_data->length = length;
if (write) {
dio_data->reserve = round_up(length, fs_info->sectorsize);
ret = btrfs_delalloc_reserve_space(BTRFS_I(inode),
&dio_data->data_reserved,
start, dio_data->reserve);
if (ret) {
extent_changeset_free(dio_data->data_reserved);
kfree(dio_data);
return ret;
}
}
iomap->private = dio_data;
/*
* If this errors out it's because we couldn't invalidate pagecache for
* this range and we need to fallback to buffered.
*/
if (lock_extent_direct(inode, lockstart, lockend, &cached_state,
create)) {
if (lock_extent_direct(inode, lockstart, lockend, &cached_state, write)) {
ret = -ENOTBLK;
goto err;
}
@ -7425,36 +7413,48 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
goto unlock_err;
}
if (create) {
ret = btrfs_get_blocks_direct_write(&em, bh_result, inode,
dio_data, start, len);
len = min(len, em->len - (start - em->start));
if (write) {
ret = btrfs_get_blocks_direct_write(&em, inode, dio_data,
start, len);
if (ret < 0)
goto unlock_err;
unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
lockend, &cached_state);
unlock_extents = true;
/* Recalc len in case the new em is smaller than requested */
len = min(len, em->len - (start - em->start));
} else {
ret = btrfs_get_blocks_direct_read(em, bh_result, inode,
start, len);
/* Can be negative only if we read from a hole */
if (ret < 0) {
ret = 0;
free_extent_map(em);
goto unlock_err;
}
/*
* We need to unlock only the end area that we aren't using.
* The rest is going to be unlocked by the endio routine.
*/
lockstart = start + bh_result->b_size;
if (lockstart < lockend) {
unlock_extent_cached(&BTRFS_I(inode)->io_tree,
lockstart, lockend, &cached_state);
} else {
free_extent_state(cached_state);
}
lockstart = start + len;
if (lockstart < lockend)
unlock_extents = true;
}
if (unlock_extents)
unlock_extent_cached(&BTRFS_I(inode)->io_tree,
lockstart, lockend, &cached_state);
else
free_extent_state(cached_state);
/*
* Translate extent map information to iomap.
* We trim the extents (and move the addr) even though iomap code does
* that, since we have locked only the parts we are performing I/O in.
*/
if ((em->block_start == EXTENT_MAP_HOLE) ||
(test_bit(EXTENT_FLAG_PREALLOC, &em->flags) && !write)) {
iomap->addr = IOMAP_NULL_ADDR;
iomap->type = IOMAP_HOLE;
} else {
iomap->addr = em->block_start + (start - em->start);
iomap->type = IOMAP_MAPPED;
}
iomap->offset = start;
iomap->bdev = fs_info->fs_devices->latest_bdev;
iomap->length = len;
free_extent_map(em);
return 0;
@ -7463,8 +7463,55 @@ unlock_err:
unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
&cached_state);
err:
if (dio_data)
current->journal_info = dio_data;
if (dio_data) {
btrfs_delalloc_release_space(BTRFS_I(inode),
dio_data->data_reserved, start,
dio_data->reserve, true);
btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->reserve);
extent_changeset_free(dio_data->data_reserved);
kfree(dio_data);
}
return ret;
}
static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
ssize_t written, unsigned int flags, struct iomap *iomap)
{
int ret = 0;
struct btrfs_dio_data *dio_data = iomap->private;
size_t submitted = dio_data->submitted;
const bool write = !!(flags & IOMAP_WRITE);
if (!write && (iomap->type == IOMAP_HOLE)) {
/* If reading from a hole, unlock and return */
unlock_extent(&BTRFS_I(inode)->io_tree, pos, pos + length - 1);
goto out;
}
if (submitted < length) {
pos += submitted;
length -= submitted;
if (write)
__endio_write_update_ordered(BTRFS_I(inode), pos,
length, false);
else
unlock_extent(&BTRFS_I(inode)->io_tree, pos,
pos + length - 1);
ret = -ENOTBLK;
}
if (write) {
if (dio_data->reserve)
btrfs_delalloc_release_space(BTRFS_I(inode),
dio_data->data_reserved, pos,
dio_data->reserve, true);
btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->length);
extent_changeset_free(dio_data->data_reserved);
}
out:
kfree(dio_data);
iomap->private = NULL;
return ret;
}
@ -7488,7 +7535,7 @@ static void btrfs_dio_private_put(struct btrfs_dio_private *dip)
dip->logical_offset + dip->bytes - 1);
}
dio_end_io(dip->dio_bio);
bio_endio(dip->dio_bio);
kfree(dip);
}
@ -7722,24 +7769,11 @@ static struct btrfs_dio_private *btrfs_create_dio_private(struct bio *dio_bio,
dip->disk_bytenr = (u64)dio_bio->bi_iter.bi_sector << 9;
dip->dio_bio = dio_bio;
refcount_set(&dip->refs, 1);
if (write) {
struct btrfs_dio_data *dio_data = current->journal_info;
/*
* Setting range start and end to the same value means that
* no cleanup will happen in btrfs_direct_IO
*/
dio_data->unsubmitted_oe_range_end = dip->logical_offset +
dip->bytes;
dio_data->unsubmitted_oe_range_start =
dio_data->unsubmitted_oe_range_end;
}
return dip;
}
static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
loff_t file_offset)
static blk_qc_t btrfs_submit_direct(struct inode *inode, struct iomap *iomap,
struct bio *dio_bio, loff_t file_offset)
{
const bool write = (bio_op(dio_bio) == REQ_OP_WRITE);
const bool csum = !(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM);
@ -7756,6 +7790,7 @@ static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
int ret;
blk_status_t status;
struct btrfs_io_geometry geom;
struct btrfs_dio_data *dio_data = iomap->private;
dip = btrfs_create_dio_private(dio_bio, inode, file_offset);
if (!dip) {
@ -7764,8 +7799,8 @@ static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
file_offset + dio_bio->bi_iter.bi_size - 1);
}
dio_bio->bi_status = BLK_STS_RESOURCE;
dio_end_io(dio_bio);
return;
bio_endio(dio_bio);
return BLK_QC_T_NONE;
}
if (!write && csum) {
@ -7836,15 +7871,17 @@ static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
goto out_err;
}
dio_data->submitted += clone_len;
clone_offset += clone_len;
start_sector += clone_len >> 9;
file_offset += clone_len;
} while (submit_len > 0);
return;
return BLK_QC_T_NONE;
out_err:
dip->dio_bio->bi_status = status;
btrfs_dio_private_put(dip);
return BLK_QC_T_NONE;
}
static ssize_t check_direct_IO(struct btrfs_fs_info *fs_info,
@ -7880,37 +7917,30 @@ out:
return retval;
}
static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
static const struct iomap_ops btrfs_dio_iomap_ops = {
.iomap_begin = btrfs_dio_iomap_begin,
.iomap_end = btrfs_dio_iomap_end,
};
static const struct iomap_dio_ops btrfs_dio_ops = {
.submit_io = btrfs_submit_direct,
};
ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct btrfs_dio_data dio_data = { 0 };
struct extent_changeset *data_reserved = NULL;
loff_t offset = iocb->ki_pos;
size_t count = 0;
int flags = 0;
bool wakeup = true;
bool relock = false;
ssize_t ret;
if (check_direct_IO(fs_info, iter, offset))
return 0;
inode_dio_begin(inode);
/*
* The generic stuff only does filemap_write_and_wait_range, which
* isn't enough if we've written compressed pages to this area, so
* we need to flush the dirty pages again to make absolutely sure
* that any outstanding dirty pages are on disk.
*/
count = iov_iter_count(iter);
if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
&BTRFS_I(inode)->runtime_flags))
filemap_fdatawrite_range(inode->i_mapping, offset,
offset + count - 1);
if (iov_iter_rw(iter) == WRITE) {
/*
* If the write DIO is beyond the EOF, we need update
@ -7918,66 +7948,21 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
* not unlock the i_mutex at this case.
*/
if (offset + count <= inode->i_size) {
dio_data.overwrite = 1;
inode_unlock(inode);
relock = true;
}
ret = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved,
offset, count);
if (ret)
goto out;
/*
* We need to know how many extents we reserved so that we can
* do the accounting properly if we go over the number we
* originally calculated. Abuse current->journal_info for this.
*/
dio_data.reserve = round_up(count,
fs_info->sectorsize);
dio_data.unsubmitted_oe_range_start = (u64)offset;
dio_data.unsubmitted_oe_range_end = (u64)offset;
current->journal_info = &dio_data;
down_read(&BTRFS_I(inode)->dio_sem);
} else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,
&BTRFS_I(inode)->runtime_flags)) {
inode_dio_end(inode);
flags = DIO_LOCKING | DIO_SKIP_HOLES;
wakeup = false;
}
ret = __blockdev_direct_IO(iocb, inode,
fs_info->fs_devices->latest_bdev,
iter, btrfs_get_blocks_direct, NULL,
btrfs_submit_direct, flags);
if (iov_iter_rw(iter) == WRITE) {
ret = iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
is_sync_kiocb(iocb));
if (ret == -ENOTBLK)
ret = 0;
if (iov_iter_rw(iter) == WRITE)
up_read(&BTRFS_I(inode)->dio_sem);
current->journal_info = NULL;
if (ret < 0 && ret != -EIOCBQUEUED) {
if (dio_data.reserve)
btrfs_delalloc_release_space(BTRFS_I(inode),
data_reserved, offset, dio_data.reserve,
true);
/*
* On error we might have left some ordered extents
* without submitting corresponding bios for them, so
* cleanup them up to avoid other tasks getting them
* and waiting for them to complete forever.
*/
if (dio_data.unsubmitted_oe_range_start <
dio_data.unsubmitted_oe_range_end)
__endio_write_update_ordered(BTRFS_I(inode),
dio_data.unsubmitted_oe_range_start,
dio_data.unsubmitted_oe_range_end -
dio_data.unsubmitted_oe_range_start,
false);
} else if (ret >= 0 && (size_t)ret < count)
btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved,
offset, count - (size_t)ret, true);
btrfs_delalloc_release_extents(BTRFS_I(inode), count);
}
out:
if (wakeup)
inode_dio_end(inode);
if (relock)
inode_lock(inode);
@ -10209,7 +10194,7 @@ static const struct address_space_operations btrfs_aops = {
.writepage = btrfs_writepage,
.writepages = btrfs_writepages,
.readahead = btrfs_readahead,
.direct_IO = btrfs_direct_IO,
.direct_IO = noop_direct_IO,
.invalidatepage = btrfs_invalidatepage,
.releasepage = btrfs_releasepage,
#ifdef CONFIG_MIGRATION