On Mon, Jan 11, 2021 at 03:35:24PM -0500, Josef Bacik wrote: > On 1/11/21 3:21 PM, Omar Sandoval wrote: > > On Thu, Dec 03, 2020 at 09:32:37AM -0500, Josef Bacik wrote: > > > On 11/18/20 2:18 PM, Omar Sandoval wrote: > > > > From: Omar Sandoval <[email protected]> > > > > > > > > There are 4 main cases: > > > > > > > > 1. Inline extents: we copy the data straight out of the extent buffer. > > > > 2. Hole/preallocated extents: we fill in zeroes. > > > > 3. Regular, uncompressed extents: we read the sectors we need directly > > > > from disk. > > > > 4. Regular, compressed extents: we read the entire compressed extent > > > > from disk and indicate what subset of the decompressed extent is in > > > > the file. > > > > > > > > This initial implementation simplifies a few things that can be improved > > > > in the future: > > > > > > > > - We hold the inode lock during the operation. > > > > - Cases 1, 3, and 4 allocate temporary memory to read into before > > > > copying out to userspace. > > > > - We don't do read repair, because it turns out that read repair is > > > > currently broken for compressed data. > > > > > > > > Signed-off-by: Omar Sandoval <[email protected]> > > > > --- > > > > fs/btrfs/ctree.h | 2 + > > > > fs/btrfs/file.c | 5 + > > > > fs/btrfs/inode.c | 496 > > > > +++++++++++++++++++++++++++++++++++++++++++++++ > > > > 3 files changed, 503 insertions(+) > > > > > > > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > > > > index 6ab2ab002bf6..ce78424f1d98 100644 > > > > --- a/fs/btrfs/ctree.h > > > > +++ b/fs/btrfs/ctree.h > > > > @@ -3133,6 +3133,8 @@ int btrfs_run_delalloc_range(struct btrfs_inode > > > > *inode, struct page *locked_page > > > > 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); > > > > +ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter); > > > > + > > > > extern const struct dentry_operations btrfs_dentry_operations; > > > > extern const struct iomap_ops btrfs_dio_iomap_ops; > > > > extern const struct iomap_dio_ops btrfs_dio_ops; > > > > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c > > > > index 224295f8f1e1..193477565200 100644 > > > > --- a/fs/btrfs/file.c > > > > +++ b/fs/btrfs/file.c > > > > @@ -3629,6 +3629,11 @@ static ssize_t btrfs_file_read_iter(struct kiocb > > > > *iocb, struct iov_iter *to) > > > > { > > > > ssize_t ret = 0; > > > > + if (iocb->ki_flags & IOCB_ENCODED) { > > > > + if (iocb->ki_flags & IOCB_NOWAIT) > > > > + return -EOPNOTSUPP; > > > > + return btrfs_encoded_read(iocb, to); > > > > + } > > > > if (iocb->ki_flags & IOCB_DIRECT) { > > > > ret = btrfs_direct_read(iocb, to); > > > > if (ret < 0 || !iov_iter_count(to) || > > > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > > > > index 1ff903f5c5a4..b0e800897b3b 100644 > > > > --- a/fs/btrfs/inode.c > > > > +++ b/fs/btrfs/inode.c > > > > @@ -9936,6 +9936,502 @@ void btrfs_set_range_writeback(struct > > > > extent_io_tree *tree, u64 start, u64 end) > > > > } > > > > } > > > > +static int encoded_iov_compression_from_btrfs(unsigned int > > > > compress_type) > > > > +{ > > > > + switch (compress_type) { > > > > + case BTRFS_COMPRESS_NONE: > > > > + return ENCODED_IOV_COMPRESSION_NONE; > > > > + case BTRFS_COMPRESS_ZLIB: > > > > + return ENCODED_IOV_COMPRESSION_BTRFS_ZLIB; > > > > + case BTRFS_COMPRESS_LZO: > > > > + /* > > > > + * The LZO format depends on the page size. 64k is the > > > > maximum > > > > + * sectorsize (and thus page size) that we support. > > > > + */ > > > > + if (PAGE_SIZE < SZ_4K || PAGE_SIZE > SZ_64K) > > > > + return -EINVAL; > > > > + return ENCODED_IOV_COMPRESSION_BTRFS_LZO_4K + > > > > (PAGE_SHIFT - 12); > > > > + case BTRFS_COMPRESS_ZSTD: > > > > + return ENCODED_IOV_COMPRESSION_BTRFS_ZSTD; > > > > + default: > > > > + return -EUCLEAN; > > > > + } > > > > +} > > > > + > > > > +static ssize_t btrfs_encoded_read_inline(struct kiocb *iocb, > > > > + struct iov_iter *iter, u64 > > > > start, > > > > + u64 lockend, > > > > + struct extent_state > > > > **cached_state, > > > > + u64 extent_start, size_t count, > > > > + struct encoded_iov *encoded, > > > > + bool *unlocked) > > > > +{ > > > > + struct inode *inode = file_inode(iocb->ki_filp); > > > > + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; > > > > + struct btrfs_path *path; > > > > + struct extent_buffer *leaf; > > > > + struct btrfs_file_extent_item *item; > > > > + u64 ram_bytes; > > > > + unsigned long ptr; > > > > + void *tmp; > > > > + ssize_t ret; > > > > + > > > > + path = btrfs_alloc_path(); > > > > + if (!path) { > > > > + ret = -ENOMEM; > > > > + goto out; > > > > + } > > > > + ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root, path, > > > > + btrfs_ino(BTRFS_I(inode)), > > > > extent_start, > > > > + 0); > > > > + if (ret) { > > > > + if (ret > 0) { > > > > + /* The extent item disappeared? */ > > > > + ret = -EIO; > > > > + } > > > > + goto out; > > > > + } > > > > + leaf = path->nodes[0]; > > > > + item = btrfs_item_ptr(leaf, path->slots[0], > > > > + struct btrfs_file_extent_item); > > > > + > > > > + ram_bytes = btrfs_file_extent_ram_bytes(leaf, item); > > > > + ptr = btrfs_file_extent_inline_start(item); > > > > + > > > > + encoded->len = (min_t(u64, extent_start + ram_bytes, > > > > inode->i_size) - > > > > + iocb->ki_pos); > > > > + ret = encoded_iov_compression_from_btrfs( > > > > + btrfs_file_extent_compression(leaf, > > > > item)); > > > > + if (ret < 0) > > > > + goto out; > > > > + encoded->compression = ret; > > > > + if (encoded->compression) { > > > > + size_t inline_size; > > > > + > > > > + inline_size = btrfs_file_extent_inline_item_len(leaf, > > > > + > > > > btrfs_item_nr(path->slots[0])); > > > > + if (inline_size > count) { > > > > + ret = -ENOBUFS; > > > > + goto out; > > > > + } > > > > + count = inline_size; > > > > + encoded->unencoded_len = ram_bytes; > > > > + encoded->unencoded_offset = iocb->ki_pos - extent_start; > > > > + } else { > > > > + encoded->len = encoded->unencoded_len = count = > > > > + min_t(u64, count, encoded->len); > > > > + ptr += iocb->ki_pos - extent_start; > > > > + } > > > > + > > > > + tmp = kmalloc(count, GFP_NOFS); > > > > + if (!tmp) { > > > > + ret = -ENOMEM; > > > > + goto out; > > > > + } > > > > + read_extent_buffer(leaf, tmp, ptr, count); > > > > + btrfs_release_path(path); > > > > + unlock_extent_cached(io_tree, start, lockend, cached_state); > > > > + inode_unlock_shared(inode); > > > > + *unlocked = true; > > > > + > > > > + ret = copy_encoded_iov_to_iter(encoded, iter); > > > > + if (ret) > > > > + goto out_free; > > > > + ret = copy_to_iter(tmp, count, iter); > > > > + if (ret != count) > > > > + ret = -EFAULT; > > > > +out_free: > > > > + kfree(tmp); > > > > +out: > > > > + btrfs_free_path(path); > > > > + return ret; > > > > +} > > > > + > > > > +struct btrfs_encoded_read_private { > > > > + struct inode *inode; > > > > + wait_queue_head_t wait; > > > > + atomic_t pending; > > > > + blk_status_t status; > > > > + bool skip_csum; > > > > +}; > > > > + > > > > +static blk_status_t submit_encoded_read_bio(struct inode *inode, > > > > + struct bio *bio, int > > > > mirror_num, > > > > + unsigned long bio_flags) > > > > +{ > > > > + struct btrfs_encoded_read_private *priv = bio->bi_private; > > > > + struct btrfs_io_bio *io_bio = btrfs_io_bio(bio); > > > > + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > > > > + blk_status_t ret; > > > > + > > > > + if (!priv->skip_csum) { > > > > + ret = btrfs_lookup_bio_sums(inode, bio, > > > > io_bio->logical, NULL); > > > > + if (ret) > > > > + return ret; > > > > + } > > > > + > > > > + ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA); > > > > + if (ret) { > > > > + btrfs_io_bio_free_csum(io_bio); > > > > + return ret; > > > > + } > > > > + > > > > + atomic_inc(&priv->pending); > > > > + ret = btrfs_map_bio(fs_info, bio, mirror_num); > > > > + if (ret) { > > > > + atomic_dec(&priv->pending); > > > > + btrfs_io_bio_free_csum(io_bio); > > > > + } > > > > + return ret; > > > > +} > > > > + > > > > +static blk_status_t btrfs_encoded_read_check_bio(struct btrfs_io_bio > > > > *io_bio) > > > > +{ > > > > + const bool uptodate = io_bio->bio.bi_status == BLK_STS_OK; > > > > + struct btrfs_encoded_read_private *priv = > > > > io_bio->bio.bi_private; > > > > + struct inode *inode = priv->inode; > > > > + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > > > > + u32 sectorsize = fs_info->sectorsize; > > > > + struct bio_vec *bvec; > > > > + struct bvec_iter_all iter_all; > > > > + u64 start = io_bio->logical; > > > > + int icsum = 0; > > > > + > > > > + if (priv->skip_csum || !uptodate) > > > > + return io_bio->bio.bi_status; > > > > + > > > > + bio_for_each_segment_all(bvec, &io_bio->bio, iter_all) { > > > > + unsigned int i, nr_sectors, pgoff; > > > > + > > > > + nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec->bv_len); > > > > + pgoff = bvec->bv_offset; > > > > + for (i = 0; i < nr_sectors; i++) { > > > > + ASSERT(pgoff < PAGE_SIZE); > > > > + if (check_data_csum(inode, io_bio, icsum, > > > > bvec->bv_page, > > > > + pgoff, start)) > > > > + return BLK_STS_IOERR; > > > > + start += sectorsize; > > > > + icsum++; > > > > + pgoff += sectorsize; > > > > + } > > > > + } > > > > + return BLK_STS_OK; > > > > +} > > > > + > > > > +static void btrfs_encoded_read_endio(struct bio *bio) > > > > +{ > > > > + struct btrfs_encoded_read_private *priv = bio->bi_private; > > > > + struct btrfs_io_bio *io_bio = btrfs_io_bio(bio); > > > > + blk_status_t status; > > > > + > > > > + status = btrfs_encoded_read_check_bio(io_bio); > > > > + if (status) { > > > > + /* > > > > + * The memory barrier implied by the > > > > atomic_dec_return() here > > > > + * pairs with the memory barrier implied by the > > > > + * atomic_dec_return() or io_wait_event() in > > > > + * btrfs_encoded_read_regular_fill_pages() to ensure > > > > that this > > > > + * write is observed before the load of status in > > > > + * btrfs_encoded_read_regular_fill_pages(). > > > > + */ > > > > + WRITE_ONCE(priv->status, status); > > > > + } > > > > + if (!atomic_dec_return(&priv->pending)) > > > > + wake_up(&priv->wait); > > > > + btrfs_io_bio_free_csum(io_bio); > > > > + bio_put(bio); > > > > +} > > > > + > > > > +static int btrfs_encoded_read_regular_fill_pages(struct inode *inode, > > > > u64 offset, > > > > + u64 disk_io_size, > > > > struct page **pages) > > > > +{ > > > > + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > > > > + struct btrfs_encoded_read_private priv = { > > > > + .inode = inode, > > > > + .pending = ATOMIC_INIT(1), > > > > + .skip_csum = BTRFS_I(inode)->flags & > > > > BTRFS_INODE_NODATASUM, > > > > + }; > > > > + unsigned long i = 0; > > > > + u64 cur = 0; > > > > + int ret; > > > > + > > > > + init_waitqueue_head(&priv.wait); > > > > + /* > > > > + * Submit bios for the extent, splitting due to bio or stripe > > > > limits as > > > > + * necessary. > > > > + */ > > > > + while (cur < disk_io_size) { > > > > + struct btrfs_io_geometry geom; > > > > + struct bio *bio = NULL; > > > > + u64 remaining; > > > > + > > > > + ret = btrfs_get_io_geometry(fs_info, BTRFS_MAP_READ, > > > > + offset + cur, disk_io_size > > > > - cur, > > > > + &geom); > > > > + if (ret) { > > > > + WRITE_ONCE(priv.status, > > > > errno_to_blk_status(ret)); > > > > + break; > > > > + } > > > > + remaining = min(geom.len, disk_io_size - cur); > > > > + while (bio || remaining) { > > > > + size_t bytes = min_t(u64, remaining, PAGE_SIZE); > > > > + > > > > + if (!bio) { > > > > + bio = btrfs_bio_alloc(offset + cur); > > > > + bio->bi_end_io = > > > > btrfs_encoded_read_endio; > > > > + bio->bi_private = &priv; > > > > + bio->bi_opf = REQ_OP_READ; > > > > + } > > > > + > > > > + if (!bytes || > > > > + bio_add_page(bio, pages[i], bytes, 0) < > > > > bytes) { > > > > + blk_status_t status; > > > > + > > > > + status = submit_encoded_read_bio(inode, > > > > bio, 0, > > > > + 0); > > > > + if (status) { > > > > + WRITE_ONCE(priv.status, status); > > > > + bio_put(bio); > > > > + goto out; > > > > + } > > > > + bio = NULL; > > > > + continue; > > > > + } > > > > + > > > > + i++; > > > > + cur += bytes; > > > > + remaining -= bytes; > > > > + } > > > > + } > > > > + > > > > +out: > > > > + if (atomic_dec_return(&priv.pending)) > > > > + io_wait_event(priv.wait, !atomic_read(&priv.pending)); > > > > + /* See btrfs_encoded_read_endio() for ordering. */ > > > > + return blk_status_to_errno(READ_ONCE(priv.status)); > > > > +} > > > > + > > > > +static ssize_t btrfs_encoded_read_regular(struct kiocb *iocb, > > > > + struct iov_iter *iter, > > > > + u64 start, u64 lockend, > > > > + struct extent_state > > > > **cached_state, > > > > + u64 offset, u64 disk_io_size, > > > > + size_t count, > > > > + const struct encoded_iov > > > > *encoded, > > > > + bool *unlocked) > > > > +{ > > > > + struct inode *inode = file_inode(iocb->ki_filp); > > > > + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; > > > > + struct page **pages; > > > > + unsigned long nr_pages, i; > > > > + u64 cur; > > > > + size_t page_offset; > > > > + ssize_t ret; > > > > + > > > > + nr_pages = DIV_ROUND_UP(disk_io_size, PAGE_SIZE); > > > > + pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS); > > > > + if (!pages) > > > > + return -ENOMEM; > > > > + for (i = 0; i < nr_pages; i++) { > > > > + pages[i] = alloc_page(GFP_NOFS | __GFP_HIGHMEM); > > > > + if (!pages[i]) { > > > > + ret = -ENOMEM; > > > > + goto out; > > > > + } > > > > + } > > > > + > > > > + ret = btrfs_encoded_read_regular_fill_pages(inode, offset, > > > > disk_io_size, > > > > + pages); > > > > + if (ret) > > > > + goto out; > > > > + > > > > + unlock_extent_cached(io_tree, start, lockend, cached_state); > > > > + inode_unlock_shared(inode); > > > > + *unlocked = true; > > > > + > > > > + ret = copy_encoded_iov_to_iter(encoded, iter); > > > > + if (ret) > > > > + goto out; > > > > + if (encoded->compression) { > > > > + i = 0; > > > > + page_offset = 0; > > > > + } else { > > > > + i = (iocb->ki_pos - start) >> PAGE_SHIFT; > > > > + page_offset = (iocb->ki_pos - start) & (PAGE_SIZE - 1); > > > > + } > > > > + cur = 0; > > > > + while (cur < count) { > > > > + size_t bytes = min_t(size_t, count - cur, > > > > + PAGE_SIZE - page_offset); > > > > + > > > > + if (copy_page_to_iter(pages[i], page_offset, bytes, > > > > + iter) != bytes) { > > > > + ret = -EFAULT; > > > > + goto out; > > > > + } > > > > + i++; > > > > + cur += bytes; > > > > + page_offset = 0; > > > > + } > > > > + ret = count; > > > > +out: > > > > + for (i = 0; i < nr_pages; i++) { > > > > + if (pages[i]) > > > > + __free_page(pages[i]); > > > > + } > > > > + kfree(pages); > > > > + return ret; > > > > +} > > > > + > > > > +ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter) > > > > +{ > > > > + struct inode *inode = file_inode(iocb->ki_filp); > > > > + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > > > > + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; > > > > + ssize_t ret; > > > > + size_t count; > > > > + u64 start, lockend, offset, disk_io_size; > > > > + struct extent_state *cached_state = NULL; > > > > + struct extent_map *em; > > > > + struct encoded_iov encoded = {}; > > > > + bool unlocked = false; > > > > + > > > > + ret = generic_encoded_read_checks(iocb, iter); > > > > + if (ret < 0) > > > > + return ret; > > > > + if (ret == 0) > > > > + return copy_encoded_iov_to_iter(&encoded, iter); > > > > + count = ret; > > > > + > > > > + file_accessed(iocb->ki_filp); > > > > + > > > > + inode_lock_shared(inode); > > > > + > > > > + if (iocb->ki_pos >= inode->i_size) { > > > > + inode_unlock_shared(inode); > > > > + return copy_encoded_iov_to_iter(&encoded, iter); > > > > + } > > > > + start = ALIGN_DOWN(iocb->ki_pos, fs_info->sectorsize); > > > > + /* > > > > + * We don't know how long the extent containing iocb->ki_pos > > > > is, but if > > > > + * it's compressed we know that it won't be longer than this. > > > > + */ > > > > + lockend = start + BTRFS_MAX_UNCOMPRESSED - 1; > > > > + > > > > + for (;;) { > > > > + struct btrfs_ordered_extent *ordered; > > > > + > > > > + ret = btrfs_wait_ordered_range(inode, start, > > > > + lockend - start + 1); > > > > + if (ret) > > > > + goto out_unlock_inode; > > > > + lock_extent_bits(io_tree, start, lockend, > > > > &cached_state); > > > > + ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), > > > > start, > > > > + lockend - start + > > > > 1); > > > > + if (!ordered) > > > > + break; > > > > + btrfs_put_ordered_extent(ordered); > > > > + unlock_extent_cached(io_tree, start, lockend, > > > > &cached_state); > > > > + cond_resched(); > > > > + } > > > > > > This can be replaced with btrfs_lock_and_flush_ordered_range(). Then you > > > can add > > > > Sorry, finally getting back to this after the break. Please correct me > > if I'm wrong, but I don't think btrfs_lock_and_flush_ordered_range() is > > strong enough here. > > > > An encoded read needs to make sure that any buffered writes are on disk > > (since it's basically direct I/O). btrfs_lock_and_flush_ordered_range() > > bails immediately if there aren't any ordered extents. As far as I can > > tell, ordered extents aren't created until writepage, so if I do some > > buffered writes and call btrfs_lock_and_flush_ordered_range() before > > writepage creates the ordered extents, it won't flush the buffered > > writes like I need it to. This loop with btrfs_wait_ordered_range() > > does. > > > > I didn't realize that btrfs_wait_ordered_range() does the fdatawrite_range, > awesome. You can leave it then and add my reviewed-by. Thanks,
Yeah btrfs_wait_ordered_range() leaves something to be desired in naming. Thanks!
