[linux-block.git] / fs / remap_range.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/sched/xacct.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/export.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/splice.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/fs.h>
#include "internal.h"

#include <linux/uaccess.h>
#include <asm/unistd.h>

/*
 * Performs necessary checks before doing a clone.
 *
 * Can adjust amount of bytes to clone via @req_count argument.
 * Returns appropriate error code that caller should return or
 * zero in case the clone should be allowed.
 */
static int generic_remap_checks(struct file *file_in, loff_t pos_in,
				struct file *file_out, loff_t pos_out,
				loff_t *req_count, unsigned int remap_flags)
{
	struct inode *inode_in = file_in->f_mapping->host;
	struct inode *inode_out = file_out->f_mapping->host;
	uint64_t count = *req_count;
	uint64_t bcount;
	loff_t size_in, size_out;
	loff_t bs = inode_out->i_sb->s_blocksize;
	int ret;

	/* The start of both ranges must be aligned to an fs block. */
	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
		return -EINVAL;

	/* Ensure offsets don't wrap. */
	if (pos_in + count < pos_in || pos_out + count < pos_out)
		return -EINVAL;

	size_in = i_size_read(inode_in);
	size_out = i_size_read(inode_out);

	/* Dedupe requires both ranges to be within EOF. */
	if ((remap_flags & REMAP_FILE_DEDUP) &&
	    (pos_in >= size_in || pos_in + count > size_in ||
	     pos_out >= size_out || pos_out + count > size_out))
		return -EINVAL;

	/* Ensure the infile range is within the infile. */
	if (pos_in >= size_in)
		return -EINVAL;
	count = min(count, size_in - (uint64_t)pos_in);

	ret = generic_write_check_limits(file_out, pos_out, &count);
	if (ret)
		return ret;

	/*
	 * If the user wanted us to link to the infile's EOF, round up to the
	 * next block boundary for this check.
	 *
	 * Otherwise, make sure the count is also block-aligned, having
	 * already confirmed the starting offsets' block alignment.
	 */
	if (pos_in + count == size_in &&
	    (!(remap_flags & REMAP_FILE_DEDUP) || pos_out + count == size_out)) {
		bcount = ALIGN(size_in, bs) - pos_in;
	} else {
		if (!IS_ALIGNED(count, bs))
			count = ALIGN_DOWN(count, bs);
		bcount = count;
	}

	/* Don't allow overlapped cloning within the same file. */
	if (inode_in == inode_out &&
	    pos_out + bcount > pos_in &&
	    pos_out < pos_in + bcount)
		return -EINVAL;

	/*
	 * We shortened the request but the caller can't deal with that, so
	 * bounce the request back to userspace.
	 */
	if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
		return -EINVAL;

	*req_count = count;
	return 0;
}

static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
			     bool write)
{
	if (unlikely(pos < 0 || len < 0))
		return -EINVAL;

	if (unlikely((loff_t) (pos + len) < 0))
		return -EINVAL;

	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
}

/*
 * Ensure that we don't remap a partial EOF block in the middle of something
 * else.  Assume that the offsets have already been checked for block
 * alignment.
 *
 * For clone we only link a partial EOF block above or at the destination file's
 * EOF.  For deduplication we accept a partial EOF block only if it ends at the
 * destination file's EOF (can not link it into the middle of a file).
 *
 * Shorten the request if possible.
 */
static int generic_remap_check_len(struct inode *inode_in,
				   struct inode *inode_out,
				   loff_t pos_out,
				   loff_t *len,
				   unsigned int remap_flags)
{
	u64 blkmask = i_blocksize(inode_in) - 1;
	loff_t new_len = *len;

	if ((*len & blkmask) == 0)
		return 0;

	if (pos_out + *len < i_size_read(inode_out))
		new_len &= ~blkmask;

	if (new_len == *len)
		return 0;

	if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
		*len = new_len;
		return 0;
	}

	return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
}

/* Read a page's worth of file data into the page cache. */
static struct folio *vfs_dedupe_get_folio(struct file *file, loff_t pos)
{
	return read_mapping_folio(file->f_mapping, pos >> PAGE_SHIFT, file);
}

/*
 * Lock two folios, ensuring that we lock in offset order if the folios
 * are from the same file.
 */
static void vfs_lock_two_folios(struct folio *folio1, struct folio *folio2)
{
	/* Always lock in order of increasing index. */
	if (folio1->index > folio2->index)
		swap(folio1, folio2);

	folio_lock(folio1);
	if (folio1 != folio2)
		folio_lock(folio2);
}

/* Unlock two folios, being careful not to unlock the same folio twice. */
static void vfs_unlock_two_folios(struct folio *folio1, struct folio *folio2)
{
	folio_unlock(folio1);
	if (folio1 != folio2)
		folio_unlock(folio2);
}

/*
 * Compare extents of two files to see if they are the same.
 * Caller must have locked both inodes to prevent write races.
 */
static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
					 struct file *dest, loff_t dstoff,
					 loff_t len, bool *is_same)
{
	bool same = true;
	int error = -EINVAL;

	while (len) {
		struct folio *src_folio, *dst_folio;
		void *src_addr, *dst_addr;
		loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
				     PAGE_SIZE - offset_in_page(dstoff));

		cmp_len = min(cmp_len, len);
		if (cmp_len <= 0)
			goto out_error;

		src_folio = vfs_dedupe_get_folio(src, srcoff);
		if (IS_ERR(src_folio)) {
			error = PTR_ERR(src_folio);
			goto out_error;
		}
		dst_folio = vfs_dedupe_get_folio(dest, dstoff);
		if (IS_ERR(dst_folio)) {
			error = PTR_ERR(dst_folio);
			folio_put(src_folio);
			goto out_error;
		}

		vfs_lock_two_folios(src_folio, dst_folio);

		/*
		 * Now that we've locked both folios, make sure they're still
		 * mapped to the file data we're interested in.  If not,
		 * someone is invalidating pages on us and we lose.
		 */
		if (!folio_test_uptodate(src_folio) || !folio_test_uptodate(dst_folio) ||
		    src_folio->mapping != src->f_mapping ||
		    dst_folio->mapping != dest->f_mapping) {
			same = false;
			goto unlock;
		}

		src_addr = kmap_local_folio(src_folio,
					offset_in_folio(src_folio, srcoff));
		dst_addr = kmap_local_folio(dst_folio,
					offset_in_folio(dst_folio, dstoff));

		flush_dcache_folio(src_folio);
		flush_dcache_folio(dst_folio);

		if (memcmp(src_addr, dst_addr, cmp_len))
			same = false;

		kunmap_local(dst_addr);
		kunmap_local(src_addr);
unlock:
		vfs_unlock_two_folios(src_folio, dst_folio);
		folio_put(dst_folio);
		folio_put(src_folio);

		if (!same)
			break;

		srcoff += cmp_len;
		dstoff += cmp_len;
		len -= cmp_len;
	}

	*is_same = same;
	return 0;

out_error:
	return error;
}

/*
 * Check that the two inodes are eligible for cloning, the ranges make
 * sense, and then flush all dirty data.  Caller must ensure that the
 * inodes have been locked against any other modifications.
 *
 * If there's an error, then the usual negative error code is returned.
 * Otherwise returns 0 with *len set to the request length.
 */
int generic_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);
	bool same_inode = (inode_in == inode_out);
	int ret;

	/* Don't touch certain kinds of inodes */
	if (IS_IMMUTABLE(inode_out))
		return -EPERM;

	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
		return -ETXTBSY;

	/* Don't reflink dirs, pipes, sockets... */
	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
		return -EISDIR;
	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
		return -EINVAL;

	/* Zero length dedupe exits immediately; reflink goes to EOF. */
	if (*len == 0) {
		loff_t isize = i_size_read(inode_in);

		if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
			return 0;
		if (pos_in > isize)
			return -EINVAL;
		*len = isize - pos_in;
		if (*len == 0)
			return 0;
	}

	/* Check that we don't violate system file offset limits. */
	ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
			remap_flags);
	if (ret)
		return ret;

	/* Wait for the completion of any pending IOs on both files */
	inode_dio_wait(inode_in);
	if (!same_inode)
		inode_dio_wait(inode_out);

	ret = filemap_write_and_wait_range(inode_in->i_mapping,
			pos_in, pos_in + *len - 1);
	if (ret)
		return ret;

	ret = filemap_write_and_wait_range(inode_out->i_mapping,
			pos_out, pos_out + *len - 1);
	if (ret)
		return ret;

	/*
	 * Check that the extents are the same.
	 */
	if (remap_flags & REMAP_FILE_DEDUP) {
		bool		is_same = false;

		ret = vfs_dedupe_file_range_compare(file_in, pos_in,
				file_out, pos_out, *len, &is_same);
		if (ret)
			return ret;
		if (!is_same)
			return -EBADE;
	}

	ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
			remap_flags);
	if (ret)
		return ret;

	/* If can't alter the file contents, we're done. */
	if (!(remap_flags & REMAP_FILE_DEDUP))
		ret = file_modified(file_out);

	return ret;
}
EXPORT_SYMBOL(generic_remap_file_range_prep);

loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
			   struct file *file_out, loff_t pos_out,
			   loff_t len, unsigned int remap_flags)
{
	loff_t ret;

	WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);

	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
		return -EXDEV;

	ret = generic_file_rw_checks(file_in, file_out);
	if (ret < 0)
		return ret;

	if (!file_in->f_op->remap_file_range)
		return -EOPNOTSUPP;

	ret = remap_verify_area(file_in, pos_in, len, false);
	if (ret)
		return ret;

	ret = remap_verify_area(file_out, pos_out, len, true);
	if (ret)
		return ret;

	ret = file_in->f_op->remap_file_range(file_in, pos_in,
			file_out, pos_out, len, remap_flags);
	if (ret < 0)
		return ret;

	fsnotify_access(file_in);
	fsnotify_modify(file_out);
	return ret;
}
EXPORT_SYMBOL(do_clone_file_range);

loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
			    struct file *file_out, loff_t pos_out,
			    loff_t len, unsigned int remap_flags)
{
	loff_t ret;

	file_start_write(file_out);
	ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
				  remap_flags);
	file_end_write(file_out);

	return ret;
}
EXPORT_SYMBOL(vfs_clone_file_range);

/* Check whether we are allowed to dedupe the destination file */
static bool allow_file_dedupe(struct file *file)
{
	struct user_namespace *mnt_userns = file_mnt_user_ns(file);
	struct inode *inode = file_inode(file);

	if (capable(CAP_SYS_ADMIN))
		return true;
	if (file->f_mode & FMODE_WRITE)
		return true;
	if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)))
		return true;
	if (!inode_permission(mnt_userns, inode, MAY_WRITE))
		return true;
	return false;
}

loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
				 struct file *dst_file, loff_t dst_pos,
				 loff_t len, unsigned int remap_flags)
{
	loff_t ret;

	WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
				     REMAP_FILE_CAN_SHORTEN));

	ret = mnt_want_write_file(dst_file);
	if (ret)
		return ret;

	/*
	 * This is redundant if called from vfs_dedupe_file_range(), but other
	 * callers need it and it's not performance sesitive...
	 */
	ret = remap_verify_area(src_file, src_pos, len, false);
	if (ret)
		goto out_drop_write;

	ret = remap_verify_area(dst_file, dst_pos, len, true);
	if (ret)
		goto out_drop_write;

	ret = -EPERM;
	if (!allow_file_dedupe(dst_file))
		goto out_drop_write;

	ret = -EXDEV;
	if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
		goto out_drop_write;

	ret = -EISDIR;
	if (S_ISDIR(file_inode(dst_file)->i_mode))
		goto out_drop_write;

	ret = -EINVAL;
	if (!dst_file->f_op->remap_file_range)
		goto out_drop_write;

	if (len == 0) {
		ret = 0;
		goto out_drop_write;
	}

	ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
			dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
out_drop_write:
	mnt_drop_write_file(dst_file);

	return ret;
}
EXPORT_SYMBOL(vfs_dedupe_file_range_one);

int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
{
	struct file_dedupe_range_info *info;
	struct inode *src = file_inode(file);
	u64 off;
	u64 len;
	int i;
	int ret;
	u16 count = same->dest_count;
	loff_t deduped;

	if (!(file->f_mode & FMODE_READ))
		return -EINVAL;

	if (same->reserved1 || same->reserved2)
		return -EINVAL;

	off = same->src_offset;
	len = same->src_length;

	if (S_ISDIR(src->i_mode))
		return -EISDIR;

	if (!S_ISREG(src->i_mode))
		return -EINVAL;

	if (!file->f_op->remap_file_range)
		return -EOPNOTSUPP;

	ret = remap_verify_area(file, off, len, false);
	if (ret < 0)
		return ret;
	ret = 0;

	if (off + len > i_size_read(src))
		return -EINVAL;

	/* Arbitrary 1G limit on a single dedupe request, can be raised. */
	len = min_t(u64, len, 1 << 30);

	/* pre-format output fields to sane values */
	for (i = 0; i < count; i++) {
		same->info[i].bytes_deduped = 0ULL;
		same->info[i].status = FILE_DEDUPE_RANGE_SAME;
	}

	for (i = 0, info = same->info; i < count; i++, info++) {
		struct fd dst_fd = fdget(info->dest_fd);
		struct file *dst_file = dst_fd.file;

		if (!dst_file) {
			info->status = -EBADF;
			goto next_loop;
		}

		if (info->reserved) {
			info->status = -EINVAL;
			goto next_fdput;
		}

		deduped = vfs_dedupe_file_range_one(file, off, dst_file,
						    info->dest_offset, len,
						    REMAP_FILE_CAN_SHORTEN);
		if (deduped == -EBADE)
			info->status = FILE_DEDUPE_RANGE_DIFFERS;
		else if (deduped < 0)
			info->status = deduped;
		else
			info->bytes_deduped = len;

next_fdput:
		fdput(dst_fd);
next_loop:
		if (fatal_signal_pending(current))
			break;
	}
	return ret;
}
EXPORT_SYMBOL(vfs_dedupe_file_range);
Commit	Line	Data
02e83f46 DW	1	// SPDX-License-Identifier: GPL-2.0-only
	2	#include <linux/slab.h>
	3	#include <linux/stat.h>
	4	#include <linux/sched/xacct.h>
	5	#include <linux/fcntl.h>
	6	#include <linux/file.h>
	7	#include <linux/uio.h>
	8	#include <linux/fsnotify.h>
	9	#include <linux/security.h>
	10	#include <linux/export.h>
	11	#include <linux/syscalls.h>
	12	#include <linux/pagemap.h>
	13	#include <linux/splice.h>
	14	#include <linux/compat.h>
	15	#include <linux/mount.h>
	16	#include <linux/fs.h>
	17	#include "internal.h"
	18
	19	#include <linux/uaccess.h>
	20	#include <asm/unistd.h>
	21
	22	/*
	23	* Performs necessary checks before doing a clone.
	24	*
	25	* Can adjust amount of bytes to clone via @req_count argument.
	26	* Returns appropriate error code that caller should return or
	27	* zero in case the clone should be allowed.
	28	*/
1b2c54d6 DW	29	static int generic_remap_checks(struct file *file_in, loff_t pos_in,
	30	struct file *file_out, loff_t pos_out,
	31	loff_t *req_count, unsigned int remap_flags)
02e83f46 DW	32	{
	33	struct inode *inode_in = file_in->f_mapping->host;
	34	struct inode *inode_out = file_out->f_mapping->host;
	35	uint64_t count = *req_count;
	36	uint64_t bcount;
	37	loff_t size_in, size_out;
	38	loff_t bs = inode_out->i_sb->s_blocksize;
	39	int ret;
	40
	41	/* The start of both ranges must be aligned to an fs block. */
	42	if (!IS_ALIGNED(pos_in, bs) \|\| !IS_ALIGNED(pos_out, bs))
	43	return -EINVAL;
	44
	45	/* Ensure offsets don't wrap. */
	46	if (pos_in + count < pos_in \|\| pos_out + count < pos_out)
	47	return -EINVAL;
	48
	49	size_in = i_size_read(inode_in);
	50	size_out = i_size_read(inode_out);
	51
	52	/* Dedupe requires both ranges to be within EOF. */
	53	if ((remap_flags & REMAP_FILE_DEDUP) &&
	54	(pos_in >= size_in \|\| pos_in + count > size_in \|\|
	55	pos_out >= size_out \|\| pos_out + count > size_out))
	56	return -EINVAL;
	57
	58	/* Ensure the infile range is within the infile. */
	59	if (pos_in >= size_in)
	60	return -EINVAL;
	61	count = min(count, size_in - (uint64_t)pos_in);
	62
	63	ret = generic_write_check_limits(file_out, pos_out, &count);
	64	if (ret)
	65	return ret;
	66
	67	/*
	68	* If the user wanted us to link to the infile's EOF, round up to the
	69	* next block boundary for this check.
	70	*
	71	* Otherwise, make sure the count is also block-aligned, having
	72	* already confirmed the starting offsets' block alignment.
	73	*/
5750676b DC	74	if (pos_in + count == size_in &&
5750676b DC	75	(!(remap_flags & REMAP_FILE_DEDUP) \|\| pos_out + count == size_out)) {
02e83f46 DW	76	bcount = ALIGN(size_in, bs) - pos_in;
	77	} else {
	78	if (!IS_ALIGNED(count, bs))
	79	count = ALIGN_DOWN(count, bs);
	80	bcount = count;
	81	}
	82
	83	/* Don't allow overlapped cloning within the same file. */
	84	if (inode_in == inode_out &&
	85	pos_out + bcount > pos_in &&
	86	pos_out < pos_in + bcount)
	87	return -EINVAL;
	88
	89	/*
	90	* We shortened the request but the caller can't deal with that, so
	91	* bounce the request back to userspace.
	92	*/
	93	if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
	94	return -EINVAL;
	95
	96	*req_count = count;
	97	return 0;
	98	}
1b2c54d6 DW	99
	100	static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
	101	bool write)
	102	{
1b2c54d6 DW	103	if (unlikely(pos < 0 \|\| len < 0))
	104	return -EINVAL;
	105
	106	if (unlikely((loff_t) (pos + len) < 0))
	107	return -EINVAL;
	108
1b2c54d6 DW	109	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
	110	}
	111
	112	/*
	113	* Ensure that we don't remap a partial EOF block in the middle of something
	114	* else. Assume that the offsets have already been checked for block
	115	* alignment.
	116	*
	117	* For clone we only link a partial EOF block above or at the destination file's
	118	* EOF. For deduplication we accept a partial EOF block only if it ends at the
	119	* destination file's EOF (can not link it into the middle of a file).
	120	*
	121	* Shorten the request if possible.
	122	*/
	123	static int generic_remap_check_len(struct inode *inode_in,
	124	struct inode *inode_out,
	125	loff_t pos_out,
	126	loff_t *len,
	127	unsigned int remap_flags)
	128	{
	129	u64 blkmask = i_blocksize(inode_in) - 1;
	130	loff_t new_len = *len;
	131
	132	if ((*len & blkmask) == 0)
	133	return 0;
	134
	135	if (pos_out + *len < i_size_read(inode_out))
	136	new_len &= ~blkmask;
	137
	138	if (new_len == *len)
	139	return 0;
	140
	141	if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
	142	*len = new_len;
	143	return 0;
	144	}
	145
	146	return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
	147	}
	148
	149	/* Read a page's worth of file data into the page cache. */
4495a96c	150	static struct folio vfs_dedupe_get_folio(struct file file, loff_t pos)
1b2c54d6	151	{
da028b6b	152	return read_mapping_folio(file->f_mapping, pos >> PAGE_SHIFT, file);
1b2c54d6 DW	153	}
	154
	155	/*
338f379c MWO	156	* Lock two folios, ensuring that we lock in offset order if the folios
338f379c MWO	157	* are from the same file.
1b2c54d6	158	*/
338f379c	159	static void vfs_lock_two_folios(struct folio folio1, struct folio folio2)
1b2c54d6 DW	160	{
1b2c54d6 DW	161	/* Always lock in order of increasing index. */
338f379c MWO	162	if (folio1->index > folio2->index)
338f379c MWO	163	swap(folio1, folio2);
1b2c54d6	164
338f379c MWO	165	folio_lock(folio1);
	166	if (folio1 != folio2)
	167	folio_lock(folio2);
1b2c54d6 DW	168	}
1b2c54d6 DW	169
338f379c MWO	170	/* Unlock two folios, being careful not to unlock the same folio twice. */
338f379c MWO	171	static void vfs_unlock_two_folios(struct folio folio1, struct folio folio2)
1b2c54d6	172	{
338f379c MWO	173	folio_unlock(folio1);
	174	if (folio1 != folio2)
	175	folio_unlock(folio2);
1b2c54d6 DW	176	}
	177
	178	/*
	179	* Compare extents of two files to see if they are the same.
	180	* Caller must have locked both inodes to prevent write races.
	181	*/
4495a96c MWO	182	static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
4495a96c MWO	183	struct file *dest, loff_t dstoff,
1b2c54d6 DW	184	loff_t len, bool *is_same)
1b2c54d6 DW	185	{
338f379c MWO	186	bool same = true;
	187	int error = -EINVAL;
	188
1b2c54d6	189	while (len) {
338f379c MWO	190	struct folio src_folio, dst_folio;
	191	void src_addr, dst_addr;
	192	loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
	193	PAGE_SIZE - offset_in_page(dstoff));
	194
1b2c54d6 DW	195	cmp_len = min(cmp_len, len);
	196	if (cmp_len <= 0)
	197	goto out_error;
	198
338f379c MWO	199	src_folio = vfs_dedupe_get_folio(src, srcoff);
	200	if (IS_ERR(src_folio)) {
	201	error = PTR_ERR(src_folio);
1b2c54d6 DW	202	goto out_error;
1b2c54d6 DW	203	}
338f379c MWO	204	dst_folio = vfs_dedupe_get_folio(dest, dstoff);
	205	if (IS_ERR(dst_folio)) {
	206	error = PTR_ERR(dst_folio);
	207	folio_put(src_folio);
1b2c54d6 DW	208	goto out_error;
	209	}
	210
338f379c	211	vfs_lock_two_folios(src_folio, dst_folio);
1b2c54d6 DW	212
1b2c54d6 DW	213	/*
338f379c	214	* Now that we've locked both folios, make sure they're still
1b2c54d6 DW	215	* mapped to the file data we're interested in. If not,
	216	* someone is invalidating pages on us and we lose.
	217	*/
338f379c	218	if (!folio_test_uptodate(src_folio) \|\| !folio_test_uptodate(dst_folio) \|\|
4495a96c MWO	219	src_folio->mapping != src->f_mapping \|\|
4495a96c MWO	220	dst_folio->mapping != dest->f_mapping) {
1b2c54d6 DW	221	same = false;
	222	goto unlock;
	223	}
	224
338f379c MWO	225	src_addr = kmap_local_folio(src_folio,
	226	offset_in_folio(src_folio, srcoff));
	227	dst_addr = kmap_local_folio(dst_folio,
	228	offset_in_folio(dst_folio, dstoff));
1b2c54d6	229
338f379c MWO	230	flush_dcache_folio(src_folio);
338f379c MWO	231	flush_dcache_folio(dst_folio);
1b2c54d6	232
338f379c	233	if (memcmp(src_addr, dst_addr, cmp_len))
1b2c54d6 DW	234	same = false;
1b2c54d6 DW	235
338f379c MWO	236	kunmap_local(dst_addr);
338f379c MWO	237	kunmap_local(src_addr);
1b2c54d6	238	unlock:
338f379c MWO	239	vfs_unlock_two_folios(src_folio, dst_folio);
	240	folio_put(dst_folio);
	241	folio_put(src_folio);
1b2c54d6 DW	242
	243	if (!same)
	244	break;
	245
	246	srcoff += cmp_len;
338f379c	247	dstoff += cmp_len;
1b2c54d6 DW	248	len -= cmp_len;
	249	}
	250
	251	*is_same = same;
	252	return 0;
	253
	254	out_error:
	255	return error;
	256	}
	257
	258	/*
	259	* Check that the two inodes are eligible for cloning, the ranges make
	260	* sense, and then flush all dirty data. Caller must ensure that the
	261	* inodes have been locked against any other modifications.
	262	*
	263	* If there's an error, then the usual negative error code is returned.
	264	* Otherwise returns 0 with *len set to the request length.
	265	*/
	266	int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
	267	struct file *file_out, loff_t pos_out,
	268	loff_t *len, unsigned int remap_flags)
	269	{
	270	struct inode *inode_in = file_inode(file_in);
	271	struct inode *inode_out = file_inode(file_out);
	272	bool same_inode = (inode_in == inode_out);
	273	int ret;
	274
	275	/* Don't touch certain kinds of inodes */
	276	if (IS_IMMUTABLE(inode_out))
	277	return -EPERM;
	278
	279	if (IS_SWAPFILE(inode_in) \|\| IS_SWAPFILE(inode_out))
	280	return -ETXTBSY;
	281
	282	/* Don't reflink dirs, pipes, sockets... */
	283	if (S_ISDIR(inode_in->i_mode) \|\| S_ISDIR(inode_out->i_mode))
	284	return -EISDIR;
	285	if (!S_ISREG(inode_in->i_mode) \|\| !S_ISREG(inode_out->i_mode))
	286	return -EINVAL;
	287
	288	/* Zero length dedupe exits immediately; reflink goes to EOF. */
	289	if (*len == 0) {
	290	loff_t isize = i_size_read(inode_in);
	291
	292	if ((remap_flags & REMAP_FILE_DEDUP) \|\| pos_in == isize)
	293	return 0;
	294	if (pos_in > isize)
	295	return -EINVAL;
	296	*len = isize - pos_in;
	297	if (*len == 0)
	298	return 0;
	299	}
	300
	301	/* Check that we don't violate system file offset limits. */
	302	ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
	303	remap_flags);
	304	if (ret)
	305	return ret;
	306
	307	/* Wait for the completion of any pending IOs on both files */
	308	inode_dio_wait(inode_in);
	309	if (!same_inode)
	310	inode_dio_wait(inode_out);
	311
312	ret = filemap_write_and_wait_range(inode_in->i_mapping,
313	pos_in, pos_in + *len - 1);
314	if (ret)
315	return ret;
316
317	ret = filemap_write_and_wait_range(inode_out->i_mapping,
318	pos_out, pos_out + *len - 1);
319	if (ret)
320	return ret;
321
322	/*
323	* Check that the extents are the same.
324	*/
325	if (remap_flags & REMAP_FILE_DEDUP) {
326	bool is_same = false;
327
4495a96c MWO	328	ret = vfs_dedupe_file_range_compare(file_in, pos_in,
4495a96c MWO	329	file_out, pos_out, *len, &is_same);
1b2c54d6 DW	330	if (ret)
	331	return ret;
	332	if (!is_same)
	333	return -EBADE;
	334	}
	335
	336	ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
	337	remap_flags);
	338	if (ret)
	339	return ret;
	340
	341	/* If can't alter the file contents, we're done. */
	342	if (!(remap_flags & REMAP_FILE_DEDUP))
	343	ret = file_modified(file_out);
	344
	345	return ret;
	346	}
	347	EXPORT_SYMBOL(generic_remap_file_range_prep);
	348
	349	loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
	350	struct file *file_out, loff_t pos_out,
	351	loff_t len, unsigned int remap_flags)
	352	{
	353	loff_t ret;
	354
	355	WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
	356
1b2c54d6 DW	357	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
	358	return -EXDEV;
	359
	360	ret = generic_file_rw_checks(file_in, file_out);
	361	if (ret < 0)
	362	return ret;
	363
	364	if (!file_in->f_op->remap_file_range)
	365	return -EOPNOTSUPP;
	366
	367	ret = remap_verify_area(file_in, pos_in, len, false);
	368	if (ret)
	369	return ret;
	370
	371	ret = remap_verify_area(file_out, pos_out, len, true);
	372	if (ret)
	373	return ret;
	374
	375	ret = file_in->f_op->remap_file_range(file_in, pos_in,
	376	file_out, pos_out, len, remap_flags);
	377	if (ret < 0)
	378	return ret;
	379
	380	fsnotify_access(file_in);
	381	fsnotify_modify(file_out);
	382	return ret;
	383	}
	384	EXPORT_SYMBOL(do_clone_file_range);
	385
	386	loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
	387	struct file *file_out, loff_t pos_out,
	388	loff_t len, unsigned int remap_flags)
	389	{
	390	loff_t ret;
	391
	392	file_start_write(file_out);
	393	ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
	394	remap_flags);
	395	file_end_write(file_out);
	396
	397	return ret;
	398	}
	399	EXPORT_SYMBOL(vfs_clone_file_range);
	400
	401	/* Check whether we are allowed to dedupe the destination file */
	402	static bool allow_file_dedupe(struct file *file)
	403	{
0f5d220b CB	404	struct user_namespace *mnt_userns = file_mnt_user_ns(file);
	405	struct inode *inode = file_inode(file);
	406
1b2c54d6 DW	407	if (capable(CAP_SYS_ADMIN))
	408	return true;
	409	if (file->f_mode & FMODE_WRITE)
	410	return true;
0f5d220b	411	if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)))
1b2c54d6	412	return true;
0f5d220b	413	if (!inode_permission(mnt_userns, inode, MAY_WRITE))
1b2c54d6 DW	414	return true;
	415	return false;
	416	}
	417
	418	loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
	419	struct file *dst_file, loff_t dst_pos,
	420	loff_t len, unsigned int remap_flags)
	421	{
	422	loff_t ret;
	423
	424	WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP \|
	425	REMAP_FILE_CAN_SHORTEN));
	426
	427	ret = mnt_want_write_file(dst_file);
	428	if (ret)
	429	return ret;
	430
3078d85c MS	431	/*
	432	* This is redundant if called from vfs_dedupe_file_range(), but other
	433	* callers need it and it's not performance sesitive...
	434	*/
	435	ret = remap_verify_area(src_file, src_pos, len, false);
	436	if (ret)
	437	goto out_drop_write;
	438
1b2c54d6	439	ret = remap_verify_area(dst_file, dst_pos, len, true);
3078d85c	440	if (ret)
1b2c54d6 DW	441	goto out_drop_write;
	442
	443	ret = -EPERM;
	444	if (!allow_file_dedupe(dst_file))
	445	goto out_drop_write;
	446
	447	ret = -EXDEV;
9f5710bb	448	if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
1b2c54d6 DW	449	goto out_drop_write;
	450
	451	ret = -EISDIR;
	452	if (S_ISDIR(file_inode(dst_file)->i_mode))
	453	goto out_drop_write;
	454
	455	ret = -EINVAL;
	456	if (!dst_file->f_op->remap_file_range)
	457	goto out_drop_write;
	458
	459	if (len == 0) {
	460	ret = 0;
	461	goto out_drop_write;
	462	}
	463
	464	ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
	465	dst_pos, len, remap_flags \| REMAP_FILE_DEDUP);
	466	out_drop_write:
	467	mnt_drop_write_file(dst_file);
	468
	469	return ret;
	470	}
	471	EXPORT_SYMBOL(vfs_dedupe_file_range_one);
	472
	473	int vfs_dedupe_file_range(struct file file, struct file_dedupe_range same)
	474	{
	475	struct file_dedupe_range_info *info;
	476	struct inode *src = file_inode(file);
	477	u64 off;
	478	u64 len;
	479	int i;
	480	int ret;
	481	u16 count = same->dest_count;
	482	loff_t deduped;
	483
	484	if (!(file->f_mode & FMODE_READ))
	485	return -EINVAL;
	486
	487	if (same->reserved1 \|\| same->reserved2)
	488	return -EINVAL;
	489
	490	off = same->src_offset;
	491	len = same->src_length;
	492
	493	if (S_ISDIR(src->i_mode))
	494	return -EISDIR;
	495
	496	if (!S_ISREG(src->i_mode))
	497	return -EINVAL;
	498
	499	if (!file->f_op->remap_file_range)
	500	return -EOPNOTSUPP;
	501
	502	ret = remap_verify_area(file, off, len, false);
	503	if (ret < 0)
	504	return ret;
	505	ret = 0;
	506
	507	if (off + len > i_size_read(src))
	508	return -EINVAL;
	509
	510	/* Arbitrary 1G limit on a single dedupe request, can be raised. */
	511	len = min_t(u64, len, 1 << 30);
	512
513	/* pre-format output fields to sane values */
514	for (i = 0; i < count; i++) {
515	same->info[i].bytes_deduped = 0ULL;
516	same->info[i].status = FILE_DEDUPE_RANGE_SAME;
517	}
518
519	for (i = 0, info = same->info; i < count; i++, info++) {
520	struct fd dst_fd = fdget(info->dest_fd);
521	struct file *dst_file = dst_fd.file;
522
523	if (!dst_file) {
524	info->status = -EBADF;
525	goto next_loop;
526	}
527
528	if (info->reserved) {
529	info->status = -EINVAL;
530	goto next_fdput;
531	}
532
533	deduped = vfs_dedupe_file_range_one(file, off, dst_file,
534	info->dest_offset, len,
535	REMAP_FILE_CAN_SHORTEN);
536	if (deduped == -EBADE)
537	info->status = FILE_DEDUPE_RANGE_DIFFERS;
538	else if (deduped < 0)
539	info->status = deduped;
540	else
b926f2ad	541	info->bytes_deduped = len;
1b2c54d6 DW	542
	543	next_fdput:
	544	fdput(dst_fd);
	545	next_loop:
	546	if (fatal_signal_pending(current))
	547	break;
	548	}
	549	return ret;
	550	}
	551	EXPORT_SYMBOL(vfs_dedupe_file_range);