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-rw-r--r--fs/btrfs/reflink.c930
1 files changed, 930 insertions, 0 deletions
diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c
new file mode 100644
index 000000000..f50586ff8
--- /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;
+}