From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
I would like to move all the generic helpers for the vfs remap range
functionality (aka clonerange and dedupe) into a separate file so that
they won't be scattered across the vfs and the mm subsystems. The
eventual goal is to be able to deselect remap_range.c if none of the
filesystems need that code, but the tricky part here is picking a
stable(ish) part of the merge window to rearrange code.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/Makefile | 3 +-
fs/remap_range.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 2 +
mm/filemap.c | 81 +----------------------------------------
4 files changed, 108 insertions(+), 81 deletions(-)
create mode 100644 fs/remap_range.c
diff --git a/fs/Makefile b/fs/Makefile
index 1c7b0e3f6daa..7173350739c5 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -13,7 +13,8 @@ obj-y := open.o read_write.o file_table.o super.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o splice.o sync.o utimes.o d_path.o \
stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \
- fs_types.o fs_context.o fs_parser.o fsopen.o init.o
+ fs_types.o fs_context.o fs_parser.o fsopen.o init.o \
+ remap_range.o
ifeq ($(CONFIG_BLOCK),y)
obj-y += buffer.o block_dev.o direct-io.o mpage.o
diff --git a/fs/remap_range.c b/fs/remap_range.c
new file mode 100644
index 000000000000..e66d8c131b69
--- /dev/null
+++ b/fs/remap_range.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/remap_range.c
+ *
+ * Copyright (C) 1994-1999 Linus Torvalds
+ */
+
+#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.
+ */
+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) {
+ 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;
+}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7519ae003a08..eea754a8dd67 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3012,6 +3012,8 @@ extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
loff_t *count, unsigned int remap_flags);
+extern int generic_write_check_limits(struct file *file, loff_t pos,
+ loff_t *count);
extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
diff --git a/mm/filemap.c b/mm/filemap.c
index 99c49eeae71b..cf20e5aeb11b 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3098,8 +3098,7 @@ EXPORT_SYMBOL(read_cache_page_gfp);
* LFS limits. If pos is under the limit it becomes a short access. If it
* exceeds the limit we return -EFBIG.
*/
-static int generic_write_check_limits(struct file *file, loff_t pos,
- loff_t *count)
+int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count)
{
struct inode *inode = file->f_mapping->host;
loff_t max_size = inode->i_sb->s_maxbytes;
@@ -3161,84 +3160,6 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
}
EXPORT_SYMBOL(generic_write_checks);
-/*
- * 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.
- */
-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) {
- 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;
-}
-
-
/*
* Performs common checks before doing a file copy/clone
* from @file_in to @file_out.
