vfs: move generic_remap_checks out of mm

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@oracle.com>

diff --git a/fs/Makefile b/fs/Makefile
index 1c7b0e3..7173350 100644 (file)
--- 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 (file)
index 0000000..f0a8c70
--- /dev/null
+++ b/fs/remap_range.c
@@ -0,0 +1,97 @@
+// 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.
+ */
+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 7519ae0..eea754a 100644 (file)
--- 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 99c49ee..cf20e5a 100644 (file)
--- 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.