[PATCH v4 0/9] Fixes for major copy_file_range() issues

[PATCH v4 0/9] Fixes for major copy_file_range() issues

[Amir Goldstein]

Hi Darrick,

Following is a re-work of Dave Chinner's copy_file_range() patches.
This v4 patch set includes review tags and excludes the individual
filesystem fixes that are not related to cross-device copy.
Those patches will be sent to maintainers seperately once the
dependency patch is made available on a public branch.

I did include the FUSE patch in this posting since we got an ACK
from Miklos. You may take it or leave it.

Thanks,
Amir.

Changes since v3:
- Drop per filesystem patch for file_modified()/file_accessed()
- Fix wrong likely()
- Add Reviewed-by tags

Changes since v2:
- Re-order generic_remap_checks() fix patch before
  forking generic_copy_file_checks()
- Document @req_count helper argument (Darrick)
- Fold generic_access_check_limits() (Darrick)
- Added file_modified() helper (Darrick)
- Added xfs patch to use file_modified() helper
- Drop generic_copy_file_range_prep() helper
- Per filesystem patch for file_modified()/file_accessed()
- Post copy file_remove_privs() for ceph/generic (Darrick)

Changes since v1:
- Short read instead of EINVAL (Christoph)
- generic_file_rw_checks() helper (Darrick)
- generic_copy_file_range_prep() helper (Christoph)
- Not calling ->remap_file_range() with different sb
- Not calling ->copy_file_range() with different fs type
- Remove changes to overlayfs
- Extra fix to clone/dedupe checks

Amir Goldstein (7):
  vfs: introduce generic_file_rw_checks()
  vfs: remove redundant checks from generic_remap_checks()
  vfs: add missing checks to copy_file_range
  vfs: introduce file_modified() helper
  xfs: use file_modified() helper
  vfs: allow copy_file_range to copy across devices
  fuse: copy_file_range needs to strip setuid bits and update timestamps

Dave Chinner (2):
  vfs: introduce generic_copy_file_range()
  vfs: no fallback for ->copy_file_range

 fs/ceph/file.c     |  23 +++++++--
 fs/cifs/cifsfs.c   |   4 ++
 fs/fuse/file.c     |  29 +++++++++--
 fs/inode.c         |  20 +++++++
 fs/nfs/nfs4file.c  |  23 +++++++--
 fs/read_write.c    | 126 +++++++++++++++++++++++++--------------------
 fs/xfs/xfs_file.c  |  15 +-----
 include/linux/fs.h |   9 ++++
 mm/filemap.c       | 110 +++++++++++++++++++++++++++++++--------
 9 files changed, 259 insertions(+), 100 deletions(-)

-- 
2.17.1

[PATCH v4 1/9] vfs: introduce generic_copy_file_range()

[Amir Goldstein]

From: Dave Chinner <dchinner@redhat.com>

Right now if vfs_copy_file_range() does not use any offload
mechanism, it falls back to calling do_splice_direct(). This fails
to do basic sanity checks on the files being copied. Before we
start adding this necessarily functionality to the fallback path,
separate it out into generic_copy_file_range().

generic_copy_file_range() has the same prototype as
->copy_file_range() so that filesystems can use it in their custom
->copy_file_range() method if they so choose.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/read_write.c    | 35 ++++++++++++++++++++++++++++++++---
 include/linux/fs.h |  3 +++
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index c543d965e288..676b02fae589 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1565,6 +1565,36 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
 }
 #endif
 
+/**
+ * generic_copy_file_range - copy data between two files
+ * @file_in:	file structure to read from
+ * @pos_in:	file offset to read from
+ * @file_out:	file structure to write data to
+ * @pos_out:	file offset to write data to
+ * @len:	amount of data to copy
+ * @flags:	copy flags
+ *
+ * This is a generic filesystem helper to copy data from one file to another.
+ * It has no constraints on the source or destination file owners - the files
+ * can belong to different superblocks and different filesystem types. Short
+ * copies are allowed.
+ *
+ * This should be called from the @file_out filesystem, as per the
+ * ->copy_file_range() method.
+ *
+ * Returns the number of bytes copied or a negative error indicating the
+ * failure.
+ */
+
+ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				size_t len, unsigned int flags)
+{
+	return do_splice_direct(file_in, &pos_in, file_out, &pos_out,
+				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
+}
+EXPORT_SYMBOL(generic_copy_file_range);
+
 /*
  * copy_file_range() differs from regular file read and write in that it
  * specifically allows return partial success.  When it does so is up to
@@ -1632,9 +1662,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 			goto done;
 	}
 
-	ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
-			len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
-
+	ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+				      flags);
 done:
 	if (ret > 0) {
 		fsnotify_access(file_in);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f7fdfe93e25d..ea17858310ff 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1889,6 +1889,9 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
 		unsigned long, loff_t *, rwf_t);
 extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
 				   loff_t, size_t, unsigned int);
+extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
+				       struct file *file_out, loff_t pos_out,
+				       size_t len, unsigned int flags);
 extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 					 struct file *file_out, loff_t pos_out,
 					 loff_t *count,
-- 
2.17.1

[PATCH v4 2/9] vfs: no fallback for ->copy_file_range

[Amir Goldstein]

From: Dave Chinner <dchinner@redhat.com>

Now that we have generic_copy_file_range(), remove it as a fallback
case when offloads fail. This puts the responsibility for executing
fallbacks on the filesystems that implement ->copy_file_range and
allows us to add operational validity checks to
generic_copy_file_range().

Rework vfs_copy_file_range() to call a new do_copy_file_range()
helper to execute the copying callout, and move calls to
generic_file_copy_range() into filesystem methods where they
currently return failures.

[Amir] overlayfs is not responsible of executing the fallback.
It is the responsibility of the underlying filesystem.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/ceph/file.c    | 21 ++++++++++++++++++---
 fs/cifs/cifsfs.c  |  4 ++++
 fs/fuse/file.c    | 21 ++++++++++++++++++---
 fs/nfs/nfs4file.c | 20 +++++++++++++++++---
 fs/read_write.c   | 25 ++++++++++++++++---------
 5 files changed, 73 insertions(+), 18 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 305daf043eb0..e87f7b2023af 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1889,9 +1889,9 @@ static int is_file_size_ok(struct inode *src_inode, struct inode *dst_inode,
 	return 0;
 }
 
-static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
-				    struct file *dst_file, loff_t dst_off,
-				    size_t len, unsigned int flags)
+static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
+				      struct file *dst_file, loff_t dst_off,
+				      size_t len, unsigned int flags)
 {
 	struct inode *src_inode = file_inode(src_file);
 	struct inode *dst_inode = file_inode(dst_file);
@@ -2100,6 +2100,21 @@ static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
 	return ret;
 }
 
+static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
+				    struct file *dst_file, loff_t dst_off,
+				    size_t len, unsigned int flags)
+{
+	ssize_t ret;
+
+	ret = __ceph_copy_file_range(src_file, src_off, dst_file, dst_off,
+				     len, flags);
+
+	if (ret == -EOPNOTSUPP)
+		ret = generic_copy_file_range(src_file, src_off, dst_file,
+					      dst_off, len, flags);
+	return ret;
+}
+
 const struct file_operations ceph_file_fops = {
 	.open = ceph_open,
 	.release = ceph_release,
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index f5fcd6360056..c65823270313 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1148,6 +1148,10 @@ static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off,
 	rc = cifs_file_copychunk_range(xid, src_file, off, dst_file, destoff,
 					len, flags);
 	free_xid(xid);
+
+	if (rc == -EOPNOTSUPP)
+		rc = generic_copy_file_range(src_file, off, dst_file,
+					     destoff, len, flags);
 	return rc;
 }
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 3959f08279e6..e03901ae729b 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3097,9 +3097,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 	return err;
 }
 
-static ssize_t fuse_copy_file_range(struct file *file_in, loff_t pos_in,
-				    struct file *file_out, loff_t pos_out,
-				    size_t len, unsigned int flags)
+static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
+				      struct file *file_out, loff_t pos_out,
+				      size_t len, unsigned int flags)
 {
 	struct fuse_file *ff_in = file_in->private_data;
 	struct fuse_file *ff_out = file_out->private_data;
@@ -3173,6 +3173,21 @@ static ssize_t fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	return err;
 }
 
+static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
+				    struct file *dst_file, loff_t dst_off,
+				    size_t len, unsigned int flags)
+{
+	ssize_t ret;
+
+	ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off,
+				     len, flags);
+
+	if (ret == -EOPNOTSUPP)
+		ret = generic_copy_file_range(src_file, src_off, dst_file,
+					      dst_off, len, flags);
+	return ret;
+}
+
 static const struct file_operations fuse_file_operations = {
 	.llseek		= fuse_file_llseek,
 	.read_iter	= fuse_file_read_iter,
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index cf42a8b939e3..4842f3ab3161 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -129,9 +129,9 @@ nfs4_file_flush(struct file *file, fl_owner_t id)
 }
 
 #ifdef CONFIG_NFS_V4_2
-static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
-				    struct file *file_out, loff_t pos_out,
-				    size_t count, unsigned int flags)
+static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
+				      struct file *file_out, loff_t pos_out,
+				      size_t count, unsigned int flags)
 {
 	if (!nfs_server_capable(file_inode(file_out), NFS_CAP_COPY))
 		return -EOPNOTSUPP;
@@ -140,6 +140,20 @@ static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
 	return nfs42_proc_copy(file_in, pos_in, file_out, pos_out, count);
 }
 
+static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
+				    struct file *file_out, loff_t pos_out,
+				    size_t count, unsigned int flags)
+{
+	ssize_t ret;
+
+	ret = __nfs4_copy_file_range(file_in, pos_in, file_out, pos_out, count,
+				     flags);
+	if (ret == -EOPNOTSUPP)
+		ret = generic_copy_file_range(file_in, pos_in, file_out,
+					      pos_out, count, flags);
+	return ret;
+}
+
 static loff_t nfs4_file_llseek(struct file *filep, loff_t offset, int whence)
 {
 	loff_t ret;
diff --git a/fs/read_write.c b/fs/read_write.c
index 676b02fae589..b63dcb4e4fe9 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1595,6 +1595,19 @@ ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
 }
 EXPORT_SYMBOL(generic_copy_file_range);
 
+static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in,
+				  struct file *file_out, loff_t pos_out,
+				  size_t len, unsigned int flags)
+{
+	if (file_out->f_op->copy_file_range)
+		return file_out->f_op->copy_file_range(file_in, pos_in,
+						       file_out, pos_out,
+						       len, flags);
+
+	return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+				       flags);
+}
+
 /*
  * copy_file_range() differs from regular file read and write in that it
  * specifically allows return partial success.  When it does so is up to
@@ -1655,15 +1668,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 		}
 	}
 
-	if (file_out->f_op->copy_file_range) {
-		ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
-						      pos_out, len, flags);
-		if (ret != -EOPNOTSUPP)
-			goto done;
-	}
-
-	ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
-				      flags);
+	ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+				flags);
+	WARN_ON_ONCE(ret == -EOPNOTSUPP);
 done:
 	if (ret > 0) {
 		fsnotify_access(file_in);
-- 
2.17.1

[PATCH v4 3/9] vfs: introduce generic_file_rw_checks()

[Amir Goldstein]

Factor out helper with some checks on in/out file that are
common to clone_file_range and copy_file_range.

Suggested-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/read_write.c    | 38 +++++++++++---------------------------
 include/linux/fs.h |  1 +
 mm/filemap.c       | 24 ++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index b63dcb4e4fe9..f1900bdb3127 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1617,17 +1617,18 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 			    struct file *file_out, loff_t pos_out,
 			    size_t len, unsigned int flags)
 {
-	struct inode *inode_in = file_inode(file_in);
-	struct inode *inode_out = file_inode(file_out);
 	ssize_t ret;
 
 	if (flags != 0)
 		return -EINVAL;
 
-	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;
+	/* this could be relaxed once a method supports cross-fs copies */
+	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 (unlikely(ret))
+		return ret;
 
 	ret = rw_verify_area(READ, file_in, &pos_in, len);
 	if (unlikely(ret))
@@ -1637,15 +1638,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (unlikely(ret))
 		return ret;
 
-	if (!(file_in->f_mode & FMODE_READ) ||
-	    !(file_out->f_mode & FMODE_WRITE) ||
-	    (file_out->f_flags & O_APPEND))
-		return -EBADF;
-
-	/* this could be relaxed once a method supports cross-fs copies */
-	if (inode_in->i_sb != inode_out->i_sb)
-		return -EXDEV;
-
 	if (len == 0)
 		return 0;
 
@@ -2013,29 +2005,21 @@ 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)
 {
-	struct inode *inode_in = file_inode(file_in);
-	struct inode *inode_out = file_inode(file_out);
 	loff_t ret;
 
 	WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
 
-	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;
-
 	/*
 	 * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
 	 * the same mount. Practically, they only need to be on the same file
 	 * system.
 	 */
-	if (inode_in->i_sb != inode_out->i_sb)
+	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
 		return -EXDEV;
 
-	if (!(file_in->f_mode & FMODE_READ) ||
-	    !(file_out->f_mode & FMODE_WRITE) ||
-	    (file_out->f_flags & O_APPEND))
-		return -EBADF;
+	ret = generic_file_rw_checks(file_in, file_out);
+	if (ret < 0)
+		return ret;
 
 	if (!file_in->f_op->remap_file_range)
 		return -EOPNOTSUPP;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ea17858310ff..89b9b73eb581 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3049,6 +3049,7 @@ 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_file_rw_checks(struct file *file_in, struct file *file_out);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
diff --git a/mm/filemap.c b/mm/filemap.c
index df2006ba0cfa..a38619a4a6af 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3041,6 +3041,30 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in,
 	return 0;
 }
 
+
+/*
+ * Performs common checks before doing a file copy/clone
+ * from @file_in to @file_out.
+ */
+int generic_file_rw_checks(struct file *file_in, struct file *file_out)
+{
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
+
+	/* Don't copy 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;
+
+	if (!(file_in->f_mode & FMODE_READ) ||
+	    !(file_out->f_mode & FMODE_WRITE) ||
+	    (file_out->f_flags & O_APPEND))
+		return -EBADF;
+
+	return 0;
+}
+
 int pagecache_write_begin(struct file *file, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned flags,
 				struct page **pagep, void **fsdata)
-- 
2.17.1

[PATCH v4 4/9] vfs: remove redundant checks from generic_remap_checks()

[Amir Goldstein]

The access limit checks on input file range in generic_remap_checks()
are redundant because the input file size is guaranteed to be within
limits and pos+len are already checked to be within input file size.

Beyond the fact that the check cannot fail, if it would have failed,
it could return -EFBIG for input file range error. There is no precedent
for that. -EFBIG is returned in syscalls that would change file length.

With that call removed, we can fold generic_access_check_limits() into
generic_write_check_limits().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 mm/filemap.c | 33 ++++++++++++---------------------
 1 file changed, 12 insertions(+), 21 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index a38619a4a6af..44361928bbb0 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2895,24 +2895,11 @@ 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_access_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;
-
-	if (!(file->f_flags & O_LARGEFILE))
-		max_size = MAX_NON_LFS;
-
-	if (unlikely(pos >= max_size))
-		return -EFBIG;
-	*count = min(*count, max_size - pos);
-	return 0;
-}
-
 static 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;
 	loff_t limit = rlimit(RLIMIT_FSIZE);
 
 	if (limit != RLIM_INFINITY) {
@@ -2923,7 +2910,15 @@ static int generic_write_check_limits(struct file *file, loff_t pos,
 		*count = min(*count, limit - pos);
 	}
 
-	return generic_access_check_limits(file, pos, count);
+	if (!(file->f_flags & O_LARGEFILE))
+		max_size = MAX_NON_LFS;
+
+	if (unlikely(pos >= max_size))
+		return -EFBIG;
+
+	*count = min(*count, max_size - pos);
+
+	return 0;
 }
 
 /*
@@ -2963,7 +2958,7 @@ EXPORT_SYMBOL(generic_write_checks);
 /*
  * Performs necessary checks before doing a clone.
  *
- * Can adjust amount of bytes to 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.
  */
@@ -3001,10 +2996,6 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in,
 		return -EINVAL;
 	count = min(count, size_in - (uint64_t)pos_in);
 
-	ret = generic_access_check_limits(file_in, pos_in, &count);
-	if (ret)
-		return ret;
-
 	ret = generic_write_check_limits(file_out, pos_out, &count);
 	if (ret)
 		return ret;
-- 
2.17.1

[PATCH v4 5/9] vfs: add missing checks to copy_file_range

[Amir Goldstein]

Like the clone and dedupe interfaces we've recently fixed, the
copy_file_range() implementation is missing basic sanity, limits and
boundary condition tests on the parameters that are passed to it
from userspace. Create a new "generic_copy_file_checks()" function
modelled on the generic_remap_checks() function to provide this
missing functionality.

[Amir] Shorten copy length instead of checking pos_in limits
because input file size already abides by the limits.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/read_write.c    |  3 ++-
 include/linux/fs.h |  3 +++
 mm/filemap.c       | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index f1900bdb3127..b0fb1176b628 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1626,7 +1626,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
 		return -EXDEV;
 
-	ret = generic_file_rw_checks(file_in, file_out);
+	ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
+				       flags);
 	if (unlikely(ret))
 		return ret;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 89b9b73eb581..e4d382c4342a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3050,6 +3050,9 @@ 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_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,
+				    size_t *count, unsigned int flags);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
diff --git a/mm/filemap.c b/mm/filemap.c
index 44361928bbb0..aac71aef4c61 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3056,6 +3056,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
 	return 0;
 }
 
+/*
+ * Performs necessary checks before doing a file copy
+ *
+ * Can adjust amount of bytes to copy via @req_count argument.
+ * Returns appropriate error code that caller should return or
+ * zero in case the copy should be allowed.
+ */
+int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
+			     struct file *file_out, loff_t pos_out,
+			     size_t *req_count, unsigned int flags)
+{
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
+	uint64_t count = *req_count;
+	loff_t size_in;
+	int ret;
+
+	ret = generic_file_rw_checks(file_in, file_out);
+	if (ret)
+		return 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;
+
+	/* Ensure offsets don't wrap. */
+	if (pos_in + count < pos_in || pos_out + count < pos_out)
+		return -EOVERFLOW;
+
+	/* Shorten the copy to EOF */
+	size_in = i_size_read(inode_in);
+	if (pos_in >= size_in)
+		count = 0;
+	else
+		count = min(count, size_in - (uint64_t)pos_in);
+
+	ret = generic_write_check_limits(file_out, pos_out, &count);
+	if (ret)
+		return ret;
+
+	/* Don't allow overlapped copying within the same file. */
+	if (inode_in == inode_out &&
+	    pos_out + count > pos_in &&
+	    pos_out < pos_in + count)
+		return -EINVAL;
+
+	*req_count = count;
+	return 0;
+}
+
 int pagecache_write_begin(struct file *file, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned flags,
 				struct page **pagep, void **fsdata)
-- 
2.17.1

[PATCH v4 6/9] vfs: introduce file_modified() helper

[Amir Goldstein]

The combination of file_remove_privs() and file_update_mtime() is
quite common in filesystem ->write_iter() methods.

Modelled after the helper file_accessed(), introduce file_modified()
and use it from generic_remap_file_range_prep().

Note that the order of calling file_remove_privs() before
file_update_mtime() in the helper was matched to the more common order by
filesystems and not the current order in generic_remap_file_range_prep().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/inode.c         | 20 ++++++++++++++++++++
 fs/read_write.c    | 21 +++------------------
 include/linux/fs.h |  2 ++
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index df6542ec3b88..4348cfb14562 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1899,6 +1899,26 @@ int file_update_time(struct file *file)
 }
 EXPORT_SYMBOL(file_update_time);
 
+/* Caller must hold the file's inode lock */
+int file_modified(struct file *file)
+{
+	int err;
+
+	/*
+	 * Clear the security bits if the process is not being run by root.
+	 * This keeps people from modifying setuid and setgid binaries.
+	 */
+	err = file_remove_privs(file);
+	if (err)
+		return err;
+
+	if (unlikely(file->f_mode & FMODE_NOCMTIME))
+		return 0;
+
+	return file_update_time(file);
+}
+EXPORT_SYMBOL(file_modified);
+
 int inode_needs_sync(struct inode *inode)
 {
 	if (IS_SYNC(inode))
diff --git a/fs/read_write.c b/fs/read_write.c
index b0fb1176b628..cec7e7b1f693 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1980,25 +1980,10 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 		return ret;
 
 	/* If can't alter the file contents, we're done. */
-	if (!(remap_flags & REMAP_FILE_DEDUP)) {
-		/* Update the timestamps, since we can alter file contents. */
-		if (!(file_out->f_mode & FMODE_NOCMTIME)) {
-			ret = file_update_time(file_out);
-			if (ret)
-				return ret;
-		}
+	if (!(remap_flags & REMAP_FILE_DEDUP))
+		ret = file_modified(file_out);
 
-		/*
-		 * Clear the security bits if the process is not being run by
-		 * root.  This keeps people from modifying setuid and setgid
-		 * binaries.
-		 */
-		ret = file_remove_privs(file_out);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL(generic_remap_file_range_prep);
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e4d382c4342a..79ffa2958bd8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2177,6 +2177,8 @@ static inline void file_accessed(struct file *file)
 		touch_atime(&file->f_path);
 }
 
+extern int file_modified(struct file *file);
+
 int sync_inode(struct inode *inode, struct writeback_control *wbc);
 int sync_inode_metadata(struct inode *inode, int wait);
 
-- 
2.17.1

[PATCH v4 7/9] xfs: use file_modified() helper

[Amir Goldstein]

Note that by using the helper, the order of calling file_remove_privs()
after file_update_mtime() in xfs_file_aio_write_checks() has changed.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/xfs_file.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 76748255f843..916a35cae5e9 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -367,20 +367,7 @@ xfs_file_aio_write_checks(
 	 * lock above.  Eventually we should look into a way to avoid
 	 * the pointless lock roundtrip.
 	 */
-	if (likely(!(file->f_mode & FMODE_NOCMTIME))) {
-		error = file_update_time(file);
-		if (error)
-			return error;
-	}
-
-	/*
-	 * If we're writing the file then make sure to clear the setuid and
-	 * setgid bits if the process is not being run by root.  This keeps
-	 * people from modifying setuid and setgid binaries.
-	 */
-	if (!IS_NOSEC(inode))
-		return file_remove_privs(file);
-	return 0;
+	return file_modified(file);
 }
 
 static int
-- 
2.17.1

[PATCH v4 8/9] vfs: allow copy_file_range to copy across devices

[Amir Goldstein]

We want to enable cross-filesystem copy_file_range functionality
where possible, so push the "same superblock only" checks down to
the individual filesystem callouts so they can make their own
decisions about cross-superblock copy offload and fallack to
generic_copy_file_range() for cross-superblock copy.

[Amir] We do not call ->remap_file_range() in case the inodes are not
on the same sb and do not call ->copy_file_range() in case the inodes
are not on the same filesystem type.

This changes behavior of the copy_file_range(2) syscall, which will
now allow cross filesystem in-kernel copy.  CIFS already supports
cross-superblock copy, between two shares to the same server. This
functionality will now be available via the copy_file_range(2) syscall.

Cc: Steve French <stfrench@microsoft.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/ceph/file.c    |  4 +++-
 fs/cifs/cifsfs.c  |  2 +-
 fs/fuse/file.c    |  5 ++++-
 fs/nfs/nfs4file.c |  5 ++++-
 fs/read_write.c   | 20 ++++++++++++++------
 5 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index e87f7b2023af..4cd41ed5cc53 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1909,6 +1909,8 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
 
 	if (src_inode == dst_inode)
 		return -EINVAL;
+	if (src_inode->i_sb != dst_inode->i_sb)
+		return -EXDEV;
 	if (ceph_snap(dst_inode) != CEPH_NOSNAP)
 		return -EROFS;
 
@@ -2109,7 +2111,7 @@ static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
 	ret = __ceph_copy_file_range(src_file, src_off, dst_file, dst_off,
 				     len, flags);
 
-	if (ret == -EOPNOTSUPP)
+	if (ret == -EOPNOTSUPP || ret == -EXDEV)
 		ret = generic_copy_file_range(src_file, src_off, dst_file,
 					      dst_off, len, flags);
 	return ret;
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index c65823270313..f11eea6125c1 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1149,7 +1149,7 @@ static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off,
 					len, flags);
 	free_xid(xid);
 
-	if (rc == -EOPNOTSUPP)
+	if (rc == -EOPNOTSUPP || rc == -EXDEV)
 		rc = generic_copy_file_range(src_file, off, dst_file,
 					     destoff, len, flags);
 	return rc;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index e03901ae729b..569baf286835 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3126,6 +3126,9 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (fc->no_copy_file_range)
 		return -EOPNOTSUPP;
 
+	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
+		return -EXDEV;
+
 	inode_lock(inode_out);
 
 	if (fc->writeback_cache) {
@@ -3182,7 +3185,7 @@ static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
 	ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off,
 				     len, flags);
 
-	if (ret == -EOPNOTSUPP)
+	if (ret == -EOPNOTSUPP || ret == -EXDEV)
 		ret = generic_copy_file_range(src_file, src_off, dst_file,
 					      dst_off, len, flags);
 	return ret;
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index 4842f3ab3161..f4157eb1f69d 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -133,6 +133,9 @@ static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
 				      struct file *file_out, loff_t pos_out,
 				      size_t count, unsigned int flags)
 {
+	/* Only offload copy if superblock is the same */
+	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
+		return -EXDEV;
 	if (!nfs_server_capable(file_inode(file_out), NFS_CAP_COPY))
 		return -EOPNOTSUPP;
 	if (file_inode(file_in) == file_inode(file_out))
@@ -148,7 +151,7 @@ static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
 
 	ret = __nfs4_copy_file_range(file_in, pos_in, file_out, pos_out, count,
 				     flags);
-	if (ret == -EOPNOTSUPP)
+	if (ret == -EOPNOTSUPP || ret == -EXDEV)
 		ret = generic_copy_file_range(file_in, pos_in, file_out,
 					      pos_out, count, flags);
 	return ret;
diff --git a/fs/read_write.c b/fs/read_write.c
index cec7e7b1f693..eb3898fb3328 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1599,7 +1599,18 @@ static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in,
 				  struct file *file_out, loff_t pos_out,
 				  size_t len, unsigned int flags)
 {
-	if (file_out->f_op->copy_file_range)
+	/*
+	 * Although we now allow filesystems to handle cross sb copy, passing
+	 * an inode of the wrong filesystem type to filesystem operation can
+	 * often result in an attempt to dereference the wrong concrete inode
+	 * struct, so avoid doing that until we really have a good reason.
+	 * The incentive for passing inode from different sb to filesystem is
+	 * NFS cross server copy and for that use case, enforcing same
+	 * filesystem type is acceptable.
+	 */
+	if (file_out->f_op->copy_file_range &&
+	    file_inode(file_in)->i_sb->s_type ==
+	    file_inode(file_out)->i_sb->s_type)
 		return file_out->f_op->copy_file_range(file_in, pos_in,
 						       file_out, pos_out,
 						       len, flags);
@@ -1622,10 +1633,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (flags != 0)
 		return -EINVAL;
 
-	/* this could be relaxed once a method supports cross-fs copies */
-	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
-		return -EXDEV;
-
 	ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
 				       flags);
 	if (unlikely(ret))
@@ -1648,7 +1655,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	 * Try cloning first, this is supported by more file systems, and
 	 * more efficient if both clone and copy are supported (e.g. NFS).
 	 */
-	if (file_in->f_op->remap_file_range) {
+	if (file_in->f_op->remap_file_range &&
+	    file_inode(file_in)->i_sb == file_inode(file_out)->i_sb) {
 		loff_t cloned;
 
 		cloned = file_in->f_op->remap_file_range(file_in, pos_in,
-- 
2.17.1

[PATCH v4 9/9] fuse: copy_file_range needs to strip setuid bits and update timestamps

[Amir Goldstein]

Like ->write_iter(), we update mtime and strip setuid of dst file before
copy and like ->read_iter(), we update atime of src file after copy.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Miklos Szeredi <miklos@szeredi.hu>
---
 fs/fuse/file.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 569baf286835..eab00cd089e8 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3131,6 +3131,10 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 
 	inode_lock(inode_out);
 
+	err = file_modified(file_out);
+	if (err)
+		goto out;
+
 	if (fc->writeback_cache) {
 		err = filemap_write_and_wait_range(inode_out->i_mapping,
 						   pos_out, pos_out + len);
@@ -3172,6 +3176,7 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 		clear_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
 
 	inode_unlock(inode_out);
+	file_accessed(file_in);
 
 	return err;
 }
-- 
2.17.1