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BRT: Fix FICLONE/FICLONERANGE shortened copy
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On Linux the ioctl_ficlonerange() and ioctl_ficlone() system calls
are expected to either fully clone the specified range or return an
error.  The range may be for an entire file.  While internally ZFS
supports cloning partial ranges there's no way to return the length
cloned to the caller so we need to make this all or nothing.

As part of this change support for the REMAP_FILE_CAN_SHORTEN flag
has been added.  When REMAP_FILE_CAN_SHORTEN is set zfs_clone_range()
will return a shortened range when encountering pending dirty records.
When it's clear zfs_clone_range() will block and wait for the records
to be written out allowing the blocks to be cloned.

Furthermore, the file rangelock is held over the region being cloned
to prevent it from being modified while cloning.  This doesn't quite
provide an atomic semantics since if an error is encountered only a
portion of the range may be cloned.  This will be converted to an
error if REMAP_FILE_CAN_SHORTEN was not provided and returned to the
caller.  However, the destination file range is left in an undefined
state.

A test case has been added which exercises this functionality by
verifying that `cp --reflink=never|auto|always` works correctly.

Signed-off-by: Brian D Behlendorf <behlendo@slag12.llnl.gov>
Issue openzfs#15728
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behlendorf committed Feb 2, 2024
1 parent 2e6b3c4 commit c5a762f
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Showing 11 changed files with 222 additions and 24 deletions.
1 change: 1 addition & 0 deletions include/os/linux/zfs/sys/zfs_vfsops_os.h
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ typedef struct zfsvfs zfsvfs_t;
struct znode;

extern int zfs_bclone_enabled;
extern int zfs_bclone_wait_dirty;

/*
* This structure emulates the vfs_t from other platforms. It's purpose
Expand Down
9 changes: 9 additions & 0 deletions man/man4/zfs.4
Original file line number Diff line number Diff line change
Expand Up @@ -1159,6 +1159,15 @@ Enable the experimental block cloning feature.
If this setting is 0, then even if feature@block_cloning is enabled,
attempts to clone blocks will act as though the feature is disabled.
.
.It Sy zfs_bclone_wait_dirty Ns = Ns Sy 0 Ns | Ns 1 Pq int
When set to 1 the FICLONE and FICLONERANGE ioctls wait for dirty data to be
written to disk.
This allows the clone operation to reliably succeed when a file is
modified and then immediately cloned.
For small files this may be slower than making a copy of the file.
Therefore, this setting defaults to 0 which causes a clone operation to
immediately fail when encountering a dirty block.
.
.It Sy zfs_blake3_impl Ns = Ns Sy fastest Pq string
Select a BLAKE3 implementation.
.Pp
Expand Down
4 changes: 4 additions & 0 deletions module/os/freebsd/zfs/zfs_vfsops.c
Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,10 @@ int zfs_bclone_enabled = 1;
SYSCTL_INT(_vfs_zfs, OID_AUTO, bclone_enabled, CTLFLAG_RWTUN,
&zfs_bclone_enabled, 0, "Enable block cloning");

int zfs_bclone_wait_dirty = 0;
SYSCTL_INT(_vfs_zfs, OID_AUTO, bclone_wait_dirty, CTLFLAG_RWTUN,
&zfs_bclone_wait_dirty, 0, "Wait for dirty blocks when cloning");

struct zfs_jailparam {
int mount_snapshot;
};
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6 changes: 5 additions & 1 deletion module/os/linux/zfs/zfs_vnops_os.c
Original file line number Diff line number Diff line change
Expand Up @@ -4257,7 +4257,11 @@ module_param(zfs_delete_blocks, ulong, 0644);
MODULE_PARM_DESC(zfs_delete_blocks, "Delete files larger than N blocks async");

/* CSTYLED */
module_param(zfs_bclone_enabled, uint, 0644);
module_param(zfs_bclone_enabled, int, 0644);
MODULE_PARM_DESC(zfs_bclone_enabled, "Enable block cloning");

/* CSTYLED */
module_param(zfs_bclone_wait_dirty, int, 0644);
MODULE_PARM_DESC(zfs_bclone_wait_dirty, "Wait for dirty blocks when cloning");

#endif
47 changes: 28 additions & 19 deletions module/os/linux/zfs/zpl_file_range.c
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#include <sys/zfeature.h>

int zfs_bclone_enabled = 1;
int zfs_bclone_wait_dirty = 0;

/*
* Clone part of a file via block cloning.
Expand All @@ -40,7 +41,7 @@ int zfs_bclone_enabled = 1;
* care of that depending on how it was called.
*/
static ssize_t
__zpl_clone_file_range(struct file *src_file, loff_t src_off,
zpl_clone_file_range_impl(struct file *src_file, loff_t src_off,
struct file *dst_file, loff_t dst_off, size_t len)
{
struct inode *src_i = file_inode(src_file);
Expand Down Expand Up @@ -96,11 +97,12 @@ zpl_copy_file_range(struct file *src_file, loff_t src_off,
{
ssize_t ret;

/* Flags is reserved for future extensions and must be zero. */
if (flags != 0)
return (-EINVAL);

/* Try to do it via zfs_clone_range() */
ret = __zpl_clone_file_range(src_file, src_off,
/* Try to do it via zfs_clone_range() and allow shortening. */
ret = zpl_clone_file_range_impl(src_file, src_off,
dst_file, dst_off, len);

#ifdef HAVE_VFS_GENERIC_COPY_FILE_RANGE
Expand Down Expand Up @@ -137,6 +139,11 @@ zpl_copy_file_range(struct file *src_file, loff_t src_off,
* FIDEDUPERANGE is for turning a non-clone into a clone, that is, compare the
* range in both files and if they're the same, arrange for them to be backed
* by the same storage.
*
* REMAP_FILE_CAN_SHORTEN lets us know we can clone less than the given range
* if we want. It's designed for filesystems that may need to shorten the
* length for alignment, EOF, or any other requirement. ZFS may shorten the
* request when there is outstanding dirty data which hasn't been written.
*/
loff_t
zpl_remap_file_range(struct file *src_file, loff_t src_off,
Expand All @@ -145,24 +152,21 @@ zpl_remap_file_range(struct file *src_file, loff_t src_off,
if (flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_CAN_SHORTEN))
return (-EINVAL);

/*
* REMAP_FILE_CAN_SHORTEN lets us know we can clone less than the given
* range if we want. Its designed for filesystems that make data past
* EOF available, and don't want it to be visible in both files. ZFS
* doesn't do that, so we just turn the flag off.
*/
flags &= ~REMAP_FILE_CAN_SHORTEN;

/* No support for dedup yet */
if (flags & REMAP_FILE_DEDUP)
/* No support for dedup yet */
return (-EOPNOTSUPP);

/* Zero length means to clone everything to the end of the file */
if (len == 0)
len = i_size_read(file_inode(src_file)) - src_off;

return (__zpl_clone_file_range(src_file, src_off,
dst_file, dst_off, len));
ssize_t ret = zpl_clone_file_range_impl(src_file, src_off,
dst_file, dst_off, len);

if (!(flags & REMAP_FILE_CAN_SHORTEN) && ret >= 0 && ret != len)
ret = -EINVAL;

return (ret);
}
#endif /* HAVE_VFS_REMAP_FILE_RANGE */

Expand All @@ -179,8 +183,14 @@ zpl_clone_file_range(struct file *src_file, loff_t src_off,
if (len == 0)
len = i_size_read(file_inode(src_file)) - src_off;

return (__zpl_clone_file_range(src_file, src_off,
dst_file, dst_off, len));
/* The entire length must be cloned or this is an error. */
ssize_t ret = zpl_clone_file_range_impl(src_file, src_off,
dst_file, dst_off, len);

if (ret >= 0 && ret != len)
ret = -EINVAL;

return (ret);
}
#endif /* HAVE_VFS_CLONE_FILE_RANGE || HAVE_VFS_FILE_OPERATIONS_EXTEND */

Expand Down Expand Up @@ -214,8 +224,7 @@ zpl_ioctl_ficlone(struct file *dst_file, void *arg)

size_t len = i_size_read(file_inode(src_file));

ssize_t ret =
__zpl_clone_file_range(src_file, 0, dst_file, 0, len);
ssize_t ret = zpl_clone_file_range_impl(src_file, 0, dst_file, 0, len);

fput(src_file);

Expand Down Expand Up @@ -253,7 +262,7 @@ zpl_ioctl_ficlonerange(struct file *dst_file, void __user *arg)
if (len == 0)
len = i_size_read(file_inode(src_file)) - fcr.fcr_src_offset;

ssize_t ret = __zpl_clone_file_range(src_file, fcr.fcr_src_offset,
ssize_t ret = zpl_clone_file_range_impl(src_file, fcr.fcr_src_offset,
dst_file, fcr.fcr_dest_offset, len);

fput(src_file);
Expand Down
15 changes: 12 additions & 3 deletions module/zfs/zfs_vnops.c
Original file line number Diff line number Diff line change
Expand Up @@ -1049,6 +1049,7 @@ zfs_clone_range(znode_t *inzp, uint64_t *inoffp, znode_t *outzp,
size_t maxblocks, nbps;
uint_t inblksz;
uint64_t clear_setid_bits_txg = 0;
uint64_t last_synced_txg = 0;

inoff = *inoffp;
outoff = *outoffp;
Expand Down Expand Up @@ -1287,15 +1288,23 @@ zfs_clone_range(znode_t *inzp, uint64_t *inoffp, znode_t *outzp,
}

nbps = maxblocks;
last_synced_txg = spa_last_synced_txg(dmu_objset_spa(inos));
error = dmu_read_l0_bps(inos, inzp->z_id, inoff, size, bps,
&nbps);
if (error != 0) {
/*
* If we are trying to clone a block that was created
* in the current transaction group, error will be
* EAGAIN here, which we can just return to the caller
* so it can fallback if it likes.
* in the current transaction group, the error will be
* EAGAIN here. Based on zfs_bclone_wait_dirty either
* return a shortened range to the caller so it can
* fallback, or wait for the next TXG and check again.
*/
if (error == EAGAIN && zfs_bclone_wait_dirty) {
txg_wait_synced(dmu_objset_pool(inos),
last_synced_txg + 1);
continue;
}

break;
}

Expand Down
2 changes: 1 addition & 1 deletion tests/runfiles/common.run
Original file line number Diff line number Diff line change
Expand Up @@ -631,7 +631,7 @@ tests = ['compress_001_pos', 'compress_002_pos', 'compress_003_pos',
tags = ['functional', 'compression']

[tests/functional/cp_files]
tests = ['cp_files_001_pos', 'cp_stress']
tests = ['cp_files_001_pos', 'cp_files_002_pos', 'cp_stress']
tags = ['functional', 'cp_files']

[tests/functional/crtime]
Expand Down
1 change: 1 addition & 0 deletions tests/test-runner/bin/zts-report.py.in
Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,7 @@ if sys.platform.startswith('freebsd'):
'cli_root/zpool_wait/zpool_wait_trim_cancel': ['SKIP', trim_reason],
'cli_root/zpool_wait/zpool_wait_trim_flag': ['SKIP', trim_reason],
'cli_root/zfs_unshare/zfs_unshare_008_pos': ['SKIP', na_reason],
'cp_files/cp_files_002_pos': ['SKIP', na_reason],
'link_count/link_count_001': ['SKIP', na_reason],
'casenorm/mixed_create_failure': ['FAIL', 13215],
'mmap/mmap_sync_001_pos': ['SKIP', na_reason],
Expand Down
1 change: 1 addition & 0 deletions tests/zfs-tests/include/tunables.cfg
Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,7 @@ VOL_MODE vol.mode zvol_volmode
VOL_RECURSIVE vol.recursive UNSUPPORTED
VOL_USE_BLK_MQ UNSUPPORTED zvol_use_blk_mq
BCLONE_ENABLED zfs_bclone_enabled zfs_bclone_enabled
BCLONE_WAIT_DIRTY zfs_bclone_wait_dirty zfs_bclone_wait_dirty
XATTR_COMPAT xattr_compat zfs_xattr_compat
ZEVENT_LEN_MAX zevent.len_max zfs_zevent_len_max
ZEVENT_RETAIN_MAX zevent.retain_max zfs_zevent_retain_max
Expand Down
1 change: 1 addition & 0 deletions tests/zfs-tests/tests/Makefile.am
Original file line number Diff line number Diff line change
Expand Up @@ -1394,6 +1394,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
functional/compression/setup.ksh \
functional/cp_files/cleanup.ksh \
functional/cp_files/cp_files_001_pos.ksh \
functional/cp_files/cp_files_002_pos.ksh \
functional/cp_files/cp_stress.ksh \
functional/cp_files/setup.ksh \
functional/crtime/cleanup.ksh \
Expand Down
159 changes: 159 additions & 0 deletions tests/zfs-tests/tests/functional/cp_files/cp_files_002_pos.ksh
Original file line number Diff line number Diff line change
@@ -0,0 +1,159 @@
#! /bin/ksh -p
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or https://opensource.org/licenses/CDDL-1.0.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#

#
# Copyright (c) 2024 by Lawrence Livermore National Security, LLC.
#

. $STF_SUITE/include/libtest.shlib

#
# DESCRIPTION:
# Verify all cp --reflink modes work with modified file.
#
# STRATEGY:
# 1. Verify "cp --reflink=never|auto|always" behaves as expected.
# Two different modes of operation are tested.
#
# a. zfs_bclone_wait_dirty=0: FICLONE and FICLONERANGE fail with EINVAL
# when there are dirty blocks which cannot be immediately cloned.
# This is the default behavior.
#
# b. zfs_bclone_wait_dirty=1: FICLONE and FICLONERANGE wait for
# dirty blocks to be written to disk allowing the clone to succeed.
# The downside to this is it may be slow which depending on the
# situtation may defeat the point of making a clone.
#

verify_runnable "global"

if ! is_linux; then
log_unsupported "cp --reflink is a GNU coreutils option"
fi

function cleanup
{
datasetexists $TESTPOOL/cp-reflink && \
destroy_dataset $$TESTPOOL/cp-reflink -f
log_must set_tunable32 BCLONE_WAIT_DIRTY 0
}

function verify_copy
{
src_cksum=$(sha256digest $1)
dst_cksum=$(sha256digest $2)

if [[ "$src_cksum" != "$dst_cksum" ]]; then
log_must ls -l $CP_TESTDIR
log_fail "checksum mismatch ($src_cksum != $dst_cksum)"
fi
}

log_assert "Verify all cp --reflink modes work with modified file"

log_onexit cleanup

SRC_FILE=src.data
DST_FILE=dst.data
SRC_SIZE=$(($RANDOM % 2048))

# A smaller recordsize is used merely to speed up the test.
RECORDSIZE=4096

log_must zfs create -o recordsize=$RECORDSIZE $TESTPOOL/cp-reflink
CP_TESTDIR=$(get_prop mountpoint $TESTPOOL/cp-reflink)

log_must cd $CP_TESTDIR

# Never wait on dirty blocks (zfs_bclone_wait_dirty=0)
log_must set_tunable32 BCLONE_WAIT_DIRTY 0

for mode in "never" "auto" "always"; do
log_note "Checking 'cp --reflink=$mode'"

# Create a new file and immediately copy it.
log_must dd if=/dev/urandom of=$SRC_FILE bs=$RECORDSIZE count=$SRC_SIZE

if [[ "$mode" == "always" ]]; then
log_mustnot cp --reflink=$mode $SRC_FILE $DST_FILE
log_must ls -l $CP_TESTDIR
else
log_must cp --reflink=$mode $SRC_FILE $DST_FILE
verify_copy $SRC_FILE $DST_FILE
fi
log_must rm -f $DST_FILE

# Append to an existing file and immediately copy it.
sync_pool $TESTPOOL
log_must dd if=/dev/urandom of=$SRC_FILE bs=$RECORDSIZE seek=$SRC_SIZE \
count=1 conv=notrunc
if [[ "$mode" == "always" ]]; then
log_mustnot cp --reflink=$mode $SRC_FILE $DST_FILE
log_must ls -l $CP_TESTDIR
else
log_must cp --reflink=$mode $SRC_FILE $DST_FILE
verify_copy $SRC_FILE $DST_FILE
fi
log_must rm -f $DST_FILE

# Overwrite a random range of an existing file and immediately copy it.
sync_pool $TESTPOOL
log_must dd if=/dev/urandom of=$SRC_FILE bs=$((RECORDSIZE / 2)) \
seek=$(($RANDOM % $SRC_SIZE)) count=$(($RANDOM % 16)) conv=notrunc
if [[ "$mode" == "always" ]]; then
log_mustnot cp --reflink=$mode $SRC_FILE $DST_FILE
log_must ls -l $CP_TESTDIR
else
log_must cp --reflink=$mode $SRC_FILE $DST_FILE
verify_copy $SRC_FILE $DST_FILE
fi
log_must rm -f $SRC_FILE $DST_FILE
done

# Wait on dirty blocks (zfs_bclone_wait_dirty=1)
log_must set_tunable32 BCLONE_WAIT_DIRTY 1

for mode in "never" "auto" "always"; do
log_note "Checking 'cp --reflink=$mode'"

# Create a new file and immediately copy it.
log_must dd if=/dev/urandom of=$SRC_FILE bs=$RECORDSIZE count=$SRC_SIZE
log_must cp --reflink=$mode $SRC_FILE $DST_FILE
verify_copy $SRC_FILE $DST_FILE
log_must rm -f $DST_FILE

# Append to an existing file and immediately copy it.
log_must dd if=/dev/urandom of=$SRC_FILE bs=$RECORDSIZE seek=$SRC_SIZE \
count=1 conv=notrunc
log_must cp --reflink=$mode $SRC_FILE $DST_FILE
verify_copy $SRC_FILE $DST_FILE
log_must rm -f $DST_FILE

# Overwrite a random range of an existing file and immediately copy it.
log_must dd if=/dev/urandom of=$SRC_FILE bs=$((RECORDSIZE / 2)) \
seek=$(($RANDOM % $SRC_SIZE)) count=$(($RANDOM % 16)) conv=notrunc
log_must cp --reflink=$mode $SRC_FILE $DST_FILE
verify_copy $SRC_FILE $DST_FILE
log_must rm -f $SRC_FILE $DST_FILE
done

log_pass

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