From: Amir Goldstein amir73il@gmail.com
commit 10bc8e4af65946b727728d7479c028742321b60a upstream.
[backport comments for pre v5.15: - ksmbd mentions are irrelevant - ksmbd hunks were dropped - sb_write_started() is missing - assert was dropped ]
Commit 868f9f2f8e00 ("vfs: fix copy_file_range() regression in cross-fs copies") removed fallback to generic_copy_file_range() for cross-fs cases inside vfs_copy_file_range().
To preserve behavior of nfsd and ksmbd server-side-copy, the fallback to generic_copy_file_range() was added in nfsd and ksmbd code, but that call is missing sb_start_write(), fsnotify hooks and more.
Ideally, nfsd and ksmbd would pass a flag to vfs_copy_file_range() that will take care of the fallback, but that code would be subtle and we got vfs_copy_file_range() logic wrong too many times already.
Instead, add a flag to explicitly request vfs_copy_file_range() to perform only generic_copy_file_range() and let nfsd and ksmbd use this flag only in the fallback path.
This choise keeps the logic changes to minimum in the non-nfsd/ksmbd code paths to reduce the risk of further regressions.
Fixes: 868f9f2f8e00 ("vfs: fix copy_file_range() regression in cross-fs copies") Tested-by: Namjae Jeon linkinjeon@kernel.org Tested-by: Luis Henriques lhenriques@suse.de Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nfsd/vfs.c | 4 ++-- fs/read_write.c | 17 +++++++++++++---- include/linux/fs.h | 8 ++++++++ 3 files changed, 23 insertions(+), 6 deletions(-)
--- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -584,8 +584,8 @@ ssize_t nfsd_copy_file_range(struct file ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
if (ret == -EOPNOTSUPP || ret == -EXDEV) - ret = generic_copy_file_range(src, src_pos, dst, dst_pos, - count, 0); + ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, + COPY_FILE_SPLICE); return ret; }
--- a/fs/read_write.c +++ b/fs/read_write.c @@ -1419,7 +1419,9 @@ static int generic_copy_file_checks(stru * and several different sets of file_operations, but they all end up * using the same ->copy_file_range() function pointer. */ - if (file_out->f_op->copy_file_range) { + if (flags & COPY_FILE_SPLICE) { + /* cross sb splice is allowed */ + } else if (file_out->f_op->copy_file_range) { if (file_in->f_op->copy_file_range != file_out->f_op->copy_file_range) return -EXDEV; @@ -1469,8 +1471,9 @@ ssize_t vfs_copy_file_range(struct file size_t len, unsigned int flags) { ssize_t ret; + bool splice = flags & COPY_FILE_SPLICE;
- if (flags != 0) + if (flags & ~COPY_FILE_SPLICE) return -EINVAL;
ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len, @@ -1496,14 +1499,14 @@ ssize_t vfs_copy_file_range(struct file * same sb using clone, but for filesystems where both clone and copy * are supported (e.g. nfs,cifs), we only call the copy method. */ - if (file_out->f_op->copy_file_range) { + if (!splice && 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); goto done; }
- if (file_in->f_op->remap_file_range && + if (!splice && file_in->f_op->remap_file_range && file_inode(file_in)->i_sb == file_inode(file_out)->i_sb) { ret = file_in->f_op->remap_file_range(file_in, pos_in, file_out, pos_out, @@ -1523,6 +1526,8 @@ ssize_t vfs_copy_file_range(struct file * consistent story about which filesystems support copy_file_range() * and which filesystems do not, that will allow userspace tools to * make consistent desicions w.r.t using copy_file_range(). + * + * We also get here if caller (e.g. nfsd) requested COPY_FILE_SPLICE. */ ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, flags); @@ -1577,6 +1582,10 @@ SYSCALL_DEFINE6(copy_file_range, int, fd pos_out = f_out.file->f_pos; }
+ ret = -EINVAL; + if (flags != 0) + goto out; + ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len, flags); if (ret > 0) { --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1817,6 +1817,14 @@ struct dir_context { */ #define REMAP_FILE_ADVISORY (REMAP_FILE_CAN_SHORTEN)
+/* + * These flags control the behavior of vfs_copy_file_range(). + * They are not available to the user via syscall. + * + * COPY_FILE_SPLICE: call splice direct instead of fs clone/copy ops + */ +#define COPY_FILE_SPLICE (1 << 0) + struct iov_iter;
struct file_operations {