blob: b03e7891394e36c838f83a7219beb065177f5ae0 [file] [log] [blame]
// 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 "reflink.h"
#include "transaction.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 = inode->i_ctime = current_time(inode);
/*
* 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)
{
const u64 block_size = btrfs_inode_sectorsize(inode);
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;
}
set_page_extent_mapped(page);
clear_extent_bit(&inode->io_tree, file_offset, range_end,
EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
0, 0, 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) {
char *map;
map = kmap(page);
memcpy(map, data_start, datal);
flush_dcache_page(page);
kunmap(page);
} else {
ret = btrfs_decompress(comp_type, data_start, page, 0,
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) {
char *map;
map = kmap(page);
memset(map + datal, 0, block_size - datal);
flush_dcache_page(page);
kunmap(page);
}
SetPageUptodate(page);
ClearPageChecked(page);
set_page_dirty(page);
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);
ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
inline_data, size, datal,
comp_type);
goto out;
}
} 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;
ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
inline_data, size, datal, comp_type);
goto out;
}
copy_inline_extent:
ret = 0;
/*
* 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.
*/
ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
inline_data, size, datal, comp_type);
goto out;
}
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);
set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(dst)->runtime_flags);
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;
}
/**
* 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;
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) {
u64 next_key_min_offset = key.offset + 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.
*/
if (key.offset + datal <= off) {
path->slots[0]++;
goto process_slot;
} else if (key.offset >= off + len) {
break;
}
next_key_min_offset = key.offset + datal;
size = btrfs_item_size_nr(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;
ret = btrfs_replace_file_extents(inode, path, drop_start,
new_key.offset + datal - 1, &clone_info,
&trans);
if (ret)
goto out;
} else if (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 (key.offset != 0 || datal > fs_info->sectorsize)
return -EUCLEAN;
ret = clone_copy_inline_extent(inode, path, &new_key,
drop_start, datal, size,
comp, buf, &trans);
if (ret)
goto out;
}
btrfs_release_path(path);
/*
* If this is a new extent update the last_reflink_trans of both
* inodes. This is used by fsync to make sure it does not log
* multiple checksum items with overlapping ranges. For older
* extents we don't need to do it since inode logging skips the
* checksums for older extents. Also ignore holes and inline
* extents because they don't have checksums in the csum tree.
*/
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 = next_key_min_offset;
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);
ret = btrfs_replace_file_extents(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);
unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
}
static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
struct inode *inode2, u64 loff2, u64 len)
{
if (inode1 < inode2) {
swap(inode1, inode2);
swap(loff1, loff2);
} else if (inode1 == inode2 && loff2 < loff1) {
swap(loff1, loff2);
}
lock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
lock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
}
static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
struct inode *dst, u64 dst_loff)
{
const u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
int ret;
/*
* Lock destination range to serialize with concurrent readpages() 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);
return ret;
}
static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
struct inode *dst, u64 dst_loff)
{
int ret;
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 readpages() 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);
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;
bool same_inode = inode_out == inode_in;
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;
if (file_in->f_path.mnt != file_out->f_path.mnt ||
inode_in->i_sb != inode_out->i_sb)
return -EXDEV;
}
/* 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);
/*
* Since we don't lock ranges, wait for ongoing lockless dio writes (as
* any in progress could create its ordered extents after we wait for
* existing ordered extents below).
*/
inode_dio_wait(inode_in);
if (!same_inode)
inode_dio_wait(inode_out);
/*
* 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);
}
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)
inode_lock(src_inode);
else
lock_two_nondirectories(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)
inode_unlock(src_inode);
else
unlock_two_nondirectories(src_inode, dst_inode);
return ret < 0 ? ret : len;
}