From f85781fb505ec02891734e77f7c69a9c85c99ec3 Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Mon, 17 Aug 2020 11:18:21 -0500 Subject: [PATCH] btrfs: switch to iomap for direct IO 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 Signed-off-by: Goldwyn Rodrigues Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/Kconfig | 1 + fs/btrfs/ctree.h | 1 + fs/btrfs/file.c | 21 ++- fs/btrfs/inode.c | 325 ++++++++++++++++++++++------------------------- 4 files changed, 176 insertions(+), 172 deletions(-) diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig index 575636f6491e..68b95ad82126 100644 --- a/fs/btrfs/Kconfig +++ b/fs/btrfs/Kconfig @@ -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 diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f2d4c14fc273..eb7adc069926 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -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); diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index b859d5ae7f80..b62679382799 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -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, diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index e8a35db53369..4f0b1dbd3240 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6,7 +6,6 @@ #include #include #include -#include #include #include #include @@ -31,6 +30,7 @@ #include #include #include +#include #include #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