diff options
Diffstat (limited to 'fs/btrfs/reflink.c')
| -rw-r--r-- | fs/btrfs/reflink.c | 930 |
1 files changed, 930 insertions, 0 deletions
diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c new file mode 100644 index 000000000000..f50586ff85c8 --- /dev/null +++ b/fs/btrfs/reflink.c @@ -0,0 +1,930 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/blkdev.h> +#include <linux/iversion.h> +#include "compression.h" +#include "ctree.h" +#include "delalloc-space.h" +#include "disk-io.h" +#include "reflink.h" +#include "transaction.h" +#include "subpage.h" + +#define BTRFS_MAX_DEDUPE_LEN SZ_16M + +static int clone_finish_inode_update(struct btrfs_trans_handle *trans, + struct inode *inode, + u64 endoff, + const u64 destoff, + const u64 olen, + int no_time_update) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + int ret; + + inode_inc_iversion(inode); + if (!no_time_update) { + inode->i_mtime = current_time(inode); + inode->i_ctime = inode->i_mtime; + } + /* + * We round up to the block size at eof when determining which + * extents to clone above, but shouldn't round up the file size. + */ + if (endoff > destoff + olen) + endoff = destoff + olen; + if (endoff > inode->i_size) { + i_size_write(inode, endoff); + btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0); + } + + ret = btrfs_update_inode(trans, root, BTRFS_I(inode)); + if (ret) { + btrfs_abort_transaction(trans, ret); + btrfs_end_transaction(trans); + goto out; + } + ret = btrfs_end_transaction(trans); +out: + return ret; +} + +static int copy_inline_to_page(struct btrfs_inode *inode, + const u64 file_offset, + char *inline_data, + const u64 size, + const u64 datal, + const u8 comp_type) +{ + struct btrfs_fs_info *fs_info = inode->root->fs_info; + const u32 block_size = fs_info->sectorsize; + const u64 range_end = file_offset + block_size - 1; + const size_t inline_size = size - btrfs_file_extent_calc_inline_size(0); + char *data_start = inline_data + btrfs_file_extent_calc_inline_size(0); + struct extent_changeset *data_reserved = NULL; + struct page *page = NULL; + struct address_space *mapping = inode->vfs_inode.i_mapping; + int ret; + + ASSERT(IS_ALIGNED(file_offset, block_size)); + + /* + * We have flushed and locked the ranges of the source and destination + * inodes, we also have locked the inodes, so we are safe to do a + * reservation here. Also we must not do the reservation while holding + * a transaction open, otherwise we would deadlock. + */ + ret = btrfs_delalloc_reserve_space(inode, &data_reserved, file_offset, + block_size); + if (ret) + goto out; + + page = find_or_create_page(mapping, file_offset >> PAGE_SHIFT, + btrfs_alloc_write_mask(mapping)); + if (!page) { + ret = -ENOMEM; + goto out_unlock; + } + + ret = set_page_extent_mapped(page); + if (ret < 0) + goto out_unlock; + + clear_extent_bit(&inode->io_tree, file_offset, range_end, + EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, + NULL); + ret = btrfs_set_extent_delalloc(inode, file_offset, range_end, 0, NULL); + if (ret) + goto out_unlock; + + /* + * After dirtying the page our caller will need to start a transaction, + * and if we are low on metadata free space, that can cause flushing of + * delalloc for all inodes in order to get metadata space released. + * However we are holding the range locked for the whole duration of + * the clone/dedupe operation, so we may deadlock if that happens and no + * other task releases enough space. So mark this inode as not being + * possible to flush to avoid such deadlock. We will clear that flag + * when we finish cloning all extents, since a transaction is started + * after finding each extent to clone. + */ + set_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &inode->runtime_flags); + + if (comp_type == BTRFS_COMPRESS_NONE) { + memcpy_to_page(page, offset_in_page(file_offset), data_start, + datal); + } else { + ret = btrfs_decompress(comp_type, data_start, page, + offset_in_page(file_offset), + inline_size, datal); + if (ret) + goto out_unlock; + flush_dcache_page(page); + } + + /* + * If our inline data is smaller then the block/page size, then the + * remaining of the block/page is equivalent to zeroes. We had something + * like the following done: + * + * $ xfs_io -f -c "pwrite -S 0xab 0 500" file + * $ sync # (or fsync) + * $ xfs_io -c "falloc 0 4K" file + * $ xfs_io -c "pwrite -S 0xcd 4K 4K" + * + * So what's in the range [500, 4095] corresponds to zeroes. + */ + if (datal < block_size) + memzero_page(page, datal, block_size - datal); + + btrfs_page_set_uptodate(fs_info, page, file_offset, block_size); + btrfs_page_clear_checked(fs_info, page, file_offset, block_size); + btrfs_page_set_dirty(fs_info, page, file_offset, block_size); +out_unlock: + if (page) { + unlock_page(page); + put_page(page); + } + if (ret) + btrfs_delalloc_release_space(inode, data_reserved, file_offset, + block_size, true); + btrfs_delalloc_release_extents(inode, block_size); +out: + extent_changeset_free(data_reserved); + + return ret; +} + +/* + * Deal with cloning of inline extents. We try to copy the inline extent from + * the source inode to destination inode when possible. When not possible we + * copy the inline extent's data into the respective page of the inode. + */ +static int clone_copy_inline_extent(struct inode *dst, + struct btrfs_path *path, + struct btrfs_key *new_key, + const u64 drop_start, + const u64 datal, + const u64 size, + const u8 comp_type, + char *inline_data, + struct btrfs_trans_handle **trans_out) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(dst->i_sb); + struct btrfs_root *root = BTRFS_I(dst)->root; + const u64 aligned_end = ALIGN(new_key->offset + datal, + fs_info->sectorsize); + struct btrfs_trans_handle *trans = NULL; + struct btrfs_drop_extents_args drop_args = { 0 }; + int ret; + struct btrfs_key key; + + if (new_key->offset > 0) { + ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset, + inline_data, size, datal, comp_type); + goto out; + } + + key.objectid = btrfs_ino(BTRFS_I(dst)); + key.type = BTRFS_EXTENT_DATA_KEY; + key.offset = 0; + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) { + return ret; + } else if (ret > 0) { + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { + ret = btrfs_next_leaf(root, path); + if (ret < 0) + return ret; + else if (ret > 0) + goto copy_inline_extent; + } + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + if (key.objectid == btrfs_ino(BTRFS_I(dst)) && + key.type == BTRFS_EXTENT_DATA_KEY) { + /* + * There's an implicit hole at file offset 0, copy the + * inline extent's data to the page. + */ + ASSERT(key.offset > 0); + goto copy_to_page; + } + } else if (i_size_read(dst) <= datal) { + struct btrfs_file_extent_item *ei; + + ei = btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_file_extent_item); + /* + * If it's an inline extent replace it with the source inline + * extent, otherwise copy the source inline extent data into + * the respective page at the destination inode. + */ + if (btrfs_file_extent_type(path->nodes[0], ei) == + BTRFS_FILE_EXTENT_INLINE) + goto copy_inline_extent; + + goto copy_to_page; + } + +copy_inline_extent: + /* + * We have no extent items, or we have an extent at offset 0 which may + * or may not be inlined. All these cases are dealt the same way. + */ + if (i_size_read(dst) > datal) { + /* + * At the destination offset 0 we have either a hole, a regular + * extent or an inline extent larger then the one we want to + * clone. Deal with all these cases by copying the inline extent + * data into the respective page at the destination inode. + */ + goto copy_to_page; + } + + /* + * Release path before starting a new transaction so we don't hold locks + * that would confuse lockdep. + */ + btrfs_release_path(path); + /* + * If we end up here it means were copy the inline extent into a leaf + * of the destination inode. We know we will drop or adjust at most one + * extent item in the destination root. + * + * 1 unit - adjusting old extent (we may have to split it) + * 1 unit - add new extent + * 1 unit - inode update + */ + trans = btrfs_start_transaction(root, 3); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + trans = NULL; + goto out; + } + drop_args.path = path; + drop_args.start = drop_start; + drop_args.end = aligned_end; + drop_args.drop_cache = true; + ret = btrfs_drop_extents(trans, root, BTRFS_I(dst), &drop_args); + if (ret) + goto out; + ret = btrfs_insert_empty_item(trans, root, path, new_key, size); + if (ret) + goto out; + + write_extent_buffer(path->nodes[0], inline_data, + btrfs_item_ptr_offset(path->nodes[0], + path->slots[0]), + size); + btrfs_update_inode_bytes(BTRFS_I(dst), datal, drop_args.bytes_found); + btrfs_set_inode_full_sync(BTRFS_I(dst)); + ret = btrfs_inode_set_file_extent_range(BTRFS_I(dst), 0, aligned_end); +out: + if (!ret && !trans) { + /* + * No transaction here means we copied the inline extent into a + * page of the destination inode. + * + * 1 unit to update inode item + */ + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + trans = NULL; + } + } + if (ret && trans) { + btrfs_abort_transaction(trans, ret); + btrfs_end_transaction(trans); + } + if (!ret) + *trans_out = trans; + + return ret; + +copy_to_page: + /* + * Release our path because we don't need it anymore and also because + * copy_inline_to_page() needs to reserve data and metadata, which may + * need to flush delalloc when we are low on available space and + * therefore cause a deadlock if writeback of an inline extent needs to + * write to the same leaf or an ordered extent completion needs to write + * to the same leaf. + */ + btrfs_release_path(path); + + ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset, + inline_data, size, datal, comp_type); + goto out; +} + +/** + * btrfs_clone() - clone a range from inode file to another + * + * @src: Inode to clone from + * @inode: Inode to clone to + * @off: Offset within source to start clone from + * @olen: Original length, passed by user, of range to clone + * @olen_aligned: Block-aligned value of olen + * @destoff: Offset within @inode to start clone + * @no_time_update: Whether to update mtime/ctime on the target inode + */ +static int btrfs_clone(struct inode *src, struct inode *inode, + const u64 off, const u64 olen, const u64 olen_aligned, + const u64 destoff, int no_time_update) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + struct btrfs_path *path = NULL; + struct extent_buffer *leaf; + struct btrfs_trans_handle *trans; + char *buf = NULL; + struct btrfs_key key; + u32 nritems; + int slot; + int ret; + const u64 len = olen_aligned; + u64 last_dest_end = destoff; + u64 prev_extent_end = off; + + ret = -ENOMEM; + buf = kvmalloc(fs_info->nodesize, GFP_KERNEL); + if (!buf) + return ret; + + path = btrfs_alloc_path(); + if (!path) { + kvfree(buf); + return ret; + } + + path->reada = READA_FORWARD; + /* Clone data */ + key.objectid = btrfs_ino(BTRFS_I(src)); + key.type = BTRFS_EXTENT_DATA_KEY; + key.offset = off; + + while (1) { + struct btrfs_file_extent_item *extent; + u64 extent_gen; + int type; + u32 size; + struct btrfs_key new_key; + u64 disko = 0, diskl = 0; + u64 datao = 0, datal = 0; + u8 comp; + u64 drop_start; + + /* Note the key will change type as we walk through the tree */ + ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path, + 0, 0); + if (ret < 0) + goto out; + /* + * First search, if no extent item that starts at offset off was + * found but the previous item is an extent item, it's possible + * it might overlap our target range, therefore process it. + */ + if (key.offset == off && ret > 0 && path->slots[0] > 0) { + btrfs_item_key_to_cpu(path->nodes[0], &key, + path->slots[0] - 1); + if (key.type == BTRFS_EXTENT_DATA_KEY) + path->slots[0]--; + } + + nritems = btrfs_header_nritems(path->nodes[0]); +process_slot: + if (path->slots[0] >= nritems) { + ret = btrfs_next_leaf(BTRFS_I(src)->root, path); + if (ret < 0) + goto out; + if (ret > 0) + break; + nritems = btrfs_header_nritems(path->nodes[0]); + } + leaf = path->nodes[0]; + slot = path->slots[0]; + + btrfs_item_key_to_cpu(leaf, &key, slot); + if (key.type > BTRFS_EXTENT_DATA_KEY || + key.objectid != btrfs_ino(BTRFS_I(src))) + break; + + ASSERT(key.type == BTRFS_EXTENT_DATA_KEY); + + extent = btrfs_item_ptr(leaf, slot, + struct btrfs_file_extent_item); + extent_gen = btrfs_file_extent_generation(leaf, extent); + comp = btrfs_file_extent_compression(leaf, extent); + type = btrfs_file_extent_type(leaf, extent); + if (type == BTRFS_FILE_EXTENT_REG || + type == BTRFS_FILE_EXTENT_PREALLOC) { + disko = btrfs_file_extent_disk_bytenr(leaf, extent); + diskl = btrfs_file_extent_disk_num_bytes(leaf, extent); + datao = btrfs_file_extent_offset(leaf, extent); + datal = btrfs_file_extent_num_bytes(leaf, extent); + } else if (type == BTRFS_FILE_EXTENT_INLINE) { + /* Take upper bound, may be compressed */ + datal = btrfs_file_extent_ram_bytes(leaf, extent); + } + + /* + * The first search might have left us at an extent item that + * ends before our target range's start, can happen if we have + * holes and NO_HOLES feature enabled. + * + * Subsequent searches may leave us on a file range we have + * processed before - this happens due to a race with ordered + * extent completion for a file range that is outside our source + * range, but that range was part of a file extent item that + * also covered a leading part of our source range. + */ + if (key.offset + datal <= prev_extent_end) { + path->slots[0]++; + goto process_slot; + } else if (key.offset >= off + len) { + break; + } + + prev_extent_end = key.offset + datal; + size = btrfs_item_size(leaf, slot); + read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, slot), + size); + + btrfs_release_path(path); + + memcpy(&new_key, &key, sizeof(new_key)); + new_key.objectid = btrfs_ino(BTRFS_I(inode)); + if (off <= key.offset) + new_key.offset = key.offset + destoff - off; + else + new_key.offset = destoff; + + /* + * Deal with a hole that doesn't have an extent item that + * represents it (NO_HOLES feature enabled). + * This hole is either in the middle of the cloning range or at + * the beginning (fully overlaps it or partially overlaps it). + */ + if (new_key.offset != last_dest_end) + drop_start = last_dest_end; + else + drop_start = new_key.offset; + + if (type == BTRFS_FILE_EXTENT_REG || + type == BTRFS_FILE_EXTENT_PREALLOC) { + struct btrfs_replace_extent_info clone_info; + + /* + * a | --- range to clone ---| b + * | ------------- extent ------------- | + */ + + /* Subtract range b */ + if (key.offset + datal > off + len) + datal = off + len - key.offset; + + /* Subtract range a */ + if (off > key.offset) { + datao += off - key.offset; + datal -= off - key.offset; + } + + clone_info.disk_offset = disko; + clone_info.disk_len = diskl; + clone_info.data_offset = datao; + clone_info.data_len = datal; + clone_info.file_offset = new_key.offset; + clone_info.extent_buf = buf; + clone_info.is_new_extent = false; + clone_info.update_times = !no_time_update; + ret = btrfs_replace_file_extents(BTRFS_I(inode), path, + drop_start, new_key.offset + datal - 1, + &clone_info, &trans); + if (ret) + goto out; + } else { + ASSERT(type == BTRFS_FILE_EXTENT_INLINE); + /* + * Inline extents always have to start at file offset 0 + * and can never be bigger then the sector size. We can + * never clone only parts of an inline extent, since all + * reflink operations must start at a sector size aligned + * offset, and the length must be aligned too or end at + * the i_size (which implies the whole inlined data). + */ + ASSERT(key.offset == 0); + ASSERT(datal <= fs_info->sectorsize); + if (WARN_ON(type != BTRFS_FILE_EXTENT_INLINE) || + WARN_ON(key.offset != 0) || + WARN_ON(datal > fs_info->sectorsize)) { + ret = -EUCLEAN; + goto out; + } + + ret = clone_copy_inline_extent(inode, path, &new_key, + drop_start, datal, size, + comp, buf, &trans); + if (ret) + goto out; + } + + btrfs_release_path(path); + + /* + * Whenever we share an extent we update the last_reflink_trans + * of each inode to the current transaction. This is needed to + * make sure fsync does not log multiple checksum items with + * overlapping ranges (because some extent items might refer + * only to sections of the original extent). For the destination + * inode we do this regardless of the generation of the extents + * or even if they are inline extents or explicit holes, to make + * sure a full fsync does not skip them. For the source inode, + * we only need to update last_reflink_trans in case it's a new + * extent that is not a hole or an inline extent, to deal with + * the checksums problem on fsync. + */ + if (extent_gen == trans->transid && disko > 0) + BTRFS_I(src)->last_reflink_trans = trans->transid; + + BTRFS_I(inode)->last_reflink_trans = trans->transid; + + last_dest_end = ALIGN(new_key.offset + datal, + fs_info->sectorsize); + ret = clone_finish_inode_update(trans, inode, last_dest_end, + destoff, olen, no_time_update); + if (ret) + goto out; + if (new_key.offset + datal >= destoff + len) + break; + + btrfs_release_path(path); + key.offset = prev_extent_end; + + if (fatal_signal_pending(current)) { + ret = -EINTR; + goto out; + } + + cond_resched(); + } + ret = 0; + + if (last_dest_end < destoff + len) { + /* + * We have an implicit hole that fully or partially overlaps our + * cloning range at its end. This means that we either have the + * NO_HOLES feature enabled or the implicit hole happened due to + * mixing buffered and direct IO writes against this file. + */ + btrfs_release_path(path); + + /* + * When using NO_HOLES and we are cloning a range that covers + * only a hole (no extents) into a range beyond the current + * i_size, punching a hole in the target range will not create + * an extent map defining a hole, because the range starts at or + * beyond current i_size. If the file previously had an i_size + * greater than the new i_size set by this clone operation, we + * need to make sure the next fsync is a full fsync, so that it + * detects and logs a hole covering a range from the current + * i_size to the new i_size. If the clone range covers extents, + * besides a hole, then we know the full sync flag was already + * set by previous calls to btrfs_replace_file_extents() that + * replaced file extent items. + */ + if (last_dest_end >= i_size_read(inode)) + btrfs_set_inode_full_sync(BTRFS_I(inode)); + + ret = btrfs_replace_file_extents(BTRFS_I(inode), path, + last_dest_end, destoff + len - 1, NULL, &trans); + if (ret) + goto out; + + ret = clone_finish_inode_update(trans, inode, destoff + len, + destoff, olen, no_time_update); + } + +out: + btrfs_free_path(path); + kvfree(buf); + clear_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &BTRFS_I(inode)->runtime_flags); + + return ret; +} + +static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1, + struct inode *inode2, u64 loff2, u64 len) +{ + unlock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1, NULL); + unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1, NULL); +} + +static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1, + struct inode *inode2, u64 loff2, u64 len) +{ + u64 range1_end = loff1 + len - 1; + u64 range2_end = loff2 + len - 1; + + if (inode1 < inode2) { + swap(inode1, inode2); + swap(loff1, loff2); + swap(range1_end, range2_end); + } else if (inode1 == inode2 && loff2 < loff1) { + swap(loff1, loff2); + swap(range1_end, range2_end); + } + + lock_extent(&BTRFS_I(inode1)->io_tree, loff1, range1_end, NULL); + lock_extent(&BTRFS_I(inode2)->io_tree, loff2, range2_end, NULL); + + btrfs_assert_inode_range_clean(BTRFS_I(inode1), loff1, range1_end); + btrfs_assert_inode_range_clean(BTRFS_I(inode2), loff2, range2_end); +} + +static void btrfs_double_mmap_lock(struct inode *inode1, struct inode *inode2) +{ + if (inode1 < inode2) + swap(inode1, inode2); + down_write(&BTRFS_I(inode1)->i_mmap_lock); + down_write_nested(&BTRFS_I(inode2)->i_mmap_lock, SINGLE_DEPTH_NESTING); +} + +static void btrfs_double_mmap_unlock(struct inode *inode1, struct inode *inode2) +{ + up_write(&BTRFS_I(inode1)->i_mmap_lock); + up_write(&BTRFS_I(inode2)->i_mmap_lock); +} + +static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len, + struct inode *dst, u64 dst_loff) +{ + struct btrfs_fs_info *fs_info = BTRFS_I(src)->root->fs_info; + const u64 bs = fs_info->sb->s_blocksize; + int ret; + + /* + * Lock destination range to serialize with concurrent readahead() and + * source range to serialize with relocation. + */ + btrfs_double_extent_lock(src, loff, dst, dst_loff, len); + ret = btrfs_clone(src, dst, loff, len, ALIGN(len, bs), dst_loff, 1); + btrfs_double_extent_unlock(src, loff, dst, dst_loff, len); + + btrfs_btree_balance_dirty(fs_info); + + return ret; +} + +static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen, + struct inode *dst, u64 dst_loff) +{ + int ret = 0; + u64 i, tail_len, chunk_count; + struct btrfs_root *root_dst = BTRFS_I(dst)->root; + + spin_lock(&root_dst->root_item_lock); + if (root_dst->send_in_progress) { + btrfs_warn_rl(root_dst->fs_info, +"cannot deduplicate to root %llu while send operations are using it (%d in progress)", + root_dst->root_key.objectid, + root_dst->send_in_progress); + spin_unlock(&root_dst->root_item_lock); + return -EAGAIN; + } + root_dst->dedupe_in_progress++; + spin_unlock(&root_dst->root_item_lock); + + tail_len = olen % BTRFS_MAX_DEDUPE_LEN; + chunk_count = div_u64(olen, BTRFS_MAX_DEDUPE_LEN); + + for (i = 0; i < chunk_count; i++) { + ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN, + dst, dst_loff); + if (ret) + goto out; + + loff += BTRFS_MAX_DEDUPE_LEN; + dst_loff += BTRFS_MAX_DEDUPE_LEN; + } + + if (tail_len > 0) + ret = btrfs_extent_same_range(src, loff, tail_len, dst, dst_loff); +out: + spin_lock(&root_dst->root_item_lock); + root_dst->dedupe_in_progress--; + spin_unlock(&root_dst->root_item_lock); + + return ret; +} + +static noinline int btrfs_clone_files(struct file *file, struct file *file_src, + u64 off, u64 olen, u64 destoff) +{ + struct inode *inode = file_inode(file); + struct inode *src = file_inode(file_src); + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + int ret; + int wb_ret; + u64 len = olen; + u64 bs = fs_info->sb->s_blocksize; + + /* + * VFS's generic_remap_file_range_prep() protects us from cloning the + * eof block into the middle of a file, which would result in corruption + * if the file size is not blocksize aligned. So we don't need to check + * for that case here. + */ + if (off + len == src->i_size) + len = ALIGN(src->i_size, bs) - off; + + if (destoff > inode->i_size) { + const u64 wb_start = ALIGN_DOWN(inode->i_size, bs); + + ret = btrfs_cont_expand(BTRFS_I(inode), inode->i_size, destoff); + if (ret) + return ret; + /* + * We may have truncated the last block if the inode's size is + * not sector size aligned, so we need to wait for writeback to + * complete before proceeding further, otherwise we can race + * with cloning and attempt to increment a reference to an + * extent that no longer exists (writeback completed right after + * we found the previous extent covering eof and before we + * attempted to increment its reference count). + */ + ret = btrfs_wait_ordered_range(inode, wb_start, + destoff - wb_start); + if (ret) + return ret; + } + + /* + * Lock destination range to serialize with concurrent readahead() and + * source range to serialize with relocation. + */ + btrfs_double_extent_lock(src, off, inode, destoff, len); + ret = btrfs_clone(src, inode, off, olen, len, destoff, 0); + btrfs_double_extent_unlock(src, off, inode, destoff, len); + + /* + * We may have copied an inline extent into a page of the destination + * range, so wait for writeback to complete before truncating pages + * from the page cache. This is a rare case. + */ + wb_ret = btrfs_wait_ordered_range(inode, destoff, len); + ret = ret ? ret : wb_ret; + /* + * Truncate page cache pages so that future reads will see the cloned + * data immediately and not the previous data. + */ + truncate_inode_pages_range(&inode->i_data, + round_down(destoff, PAGE_SIZE), + round_up(destoff + len, PAGE_SIZE) - 1); + + btrfs_btree_balance_dirty(fs_info); + + return ret; +} + +static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in, + struct file *file_out, loff_t pos_out, + loff_t *len, unsigned int remap_flags) +{ + struct inode *inode_in = file_inode(file_in); + struct inode *inode_out = file_inode(file_out); + u64 bs = BTRFS_I(inode_out)->root->fs_info->sb->s_blocksize; + u64 wb_len; + int ret; + + if (!(remap_flags & REMAP_FILE_DEDUP)) { + struct btrfs_root *root_out = BTRFS_I(inode_out)->root; + + if (btrfs_root_readonly(root_out)) + return -EROFS; + + ASSERT(inode_in->i_sb == inode_out->i_sb); + } + + /* Don't make the dst file partly checksummed */ + if ((BTRFS_I(inode_in)->flags & BTRFS_INODE_NODATASUM) != + (BTRFS_I(inode_out)->flags & BTRFS_INODE_NODATASUM)) { + return -EINVAL; + } + + /* + * Now that the inodes are locked, we need to start writeback ourselves + * and can not rely on the writeback from the VFS's generic helper + * generic_remap_file_range_prep() because: + * + * 1) For compression we must call filemap_fdatawrite_range() range + * twice (btrfs_fdatawrite_range() does it for us), and the generic + * helper only calls it once; + * + * 2) filemap_fdatawrite_range(), called by the generic helper only + * waits for the writeback to complete, i.e. for IO to be done, and + * not for the ordered extents to complete. We need to wait for them + * to complete so that new file extent items are in the fs tree. + */ + if (*len == 0 && !(remap_flags & REMAP_FILE_DEDUP)) + wb_len = ALIGN(inode_in->i_size, bs) - ALIGN_DOWN(pos_in, bs); + else + wb_len = ALIGN(*len, bs); + + /* + * Workaround to make sure NOCOW buffered write reach disk as NOCOW. + * + * Btrfs' back references do not have a block level granularity, they + * work at the whole extent level. + * NOCOW buffered write without data space reserved may not be able + * to fall back to CoW due to lack of data space, thus could cause + * data loss. + * + * Here we take a shortcut by flushing the whole inode, so that all + * nocow write should reach disk as nocow before we increase the + * reference of the extent. We could do better by only flushing NOCOW + * data, but that needs extra accounting. + * + * Also we don't need to check ASYNC_EXTENT, as async extent will be + * CoWed anyway, not affecting nocow part. + */ + ret = filemap_flush(inode_in->i_mapping); + if (ret < 0) + return ret; + + ret = btrfs_wait_ordered_range(inode_in, ALIGN_DOWN(pos_in, bs), + wb_len); + if (ret < 0) + return ret; + ret = btrfs_wait_ordered_range(inode_out, ALIGN_DOWN(pos_out, bs), + wb_len); + if (ret < 0) + return ret; + + return generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out, + len, remap_flags); +} + +static bool file_sync_write(const struct file *file) +{ + if (file->f_flags & (__O_SYNC | O_DSYNC)) + return true; + if (IS_SYNC(file_inode(file))) + return true; + + return false; +} + +loff_t btrfs_remap_file_range(struct file *src_file, loff_t off, + struct file *dst_file, loff_t destoff, loff_t len, + unsigned int remap_flags) +{ + struct inode *src_inode = file_inode(src_file); + struct inode *dst_inode = file_inode(dst_file); + bool same_inode = dst_inode == src_inode; + int ret; + + if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY)) + return -EINVAL; + + if (same_inode) { + btrfs_inode_lock(src_inode, BTRFS_ILOCK_MMAP); + } else { + lock_two_nondirectories(src_inode, dst_inode); + btrfs_double_mmap_lock(src_inode, dst_inode); + } + + ret = btrfs_remap_file_range_prep(src_file, off, dst_file, destoff, + &len, remap_flags); + if (ret < 0 || len == 0) + goto out_unlock; + + if (remap_flags & REMAP_FILE_DEDUP) + ret = btrfs_extent_same(src_inode, off, len, dst_inode, destoff); + else + ret = btrfs_clone_files(dst_file, src_file, off, len, destoff); + +out_unlock: + if (same_inode) { + btrfs_inode_unlock(src_inode, BTRFS_ILOCK_MMAP); + } else { + btrfs_double_mmap_unlock(src_inode, dst_inode); + unlock_two_nondirectories(src_inode, dst_inode); + } + + /* + * If either the source or the destination file was opened with O_SYNC, + * O_DSYNC or has the S_SYNC attribute, fsync both the destination and + * source files/ranges, so that after a successful return (0) followed + * by a power failure results in the reflinked data to be readable from + * both files/ranges. + */ + if (ret == 0 && len > 0 && + (file_sync_write(src_file) || file_sync_write(dst_file))) { + ret = btrfs_sync_file(src_file, off, off + len - 1, 0); + if (ret == 0) + ret = btrfs_sync_file(dst_file, destoff, + destoff + len - 1, 0); + } + + return ret < 0 ? ret : len; +} |