This allows us to have an in-kernel copy mechanism that avoids frequent
switches between kernel and user space. This is especially useful so
NFSD can support server-side copies.
The default (flags=0) means to first attempt copy acceleration, but use
the pagecache if that fails.
I moved the rw_verify_area() calls into the fallback code since some
filesystems can handle reflinking a large range.
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Padraig Brady <P@xxxxxxxxxxxxxx>
---
v6:
- Don't reflink by default.
- Reword commit message.
---
fs/read_write.c | 36 ++++++++++++++++++++++++++----------
1 file changed, 26 insertions(+), 10 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 20f147d..1fd555c 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1329,6 +1329,24 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
}
#endif
+static ssize_t vfs_copy_fr_copy(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t len)
+{
+ ssize_t ret = rw_verify_area(READ, file_in, &pos_in, len);
+
+ if (ret >= 0) {
+ len = ret;
+ ret = rw_verify_area(WRITE, file_out, &pos_out, len);
+ if (ret >= 0)
+ len = ret;
+ }
+ if (ret < 0)
+ return ret;
+
+ return do_splice_direct(file_in, &pos_in, file_out, &pos_out, len, 0);
+}
+
/*
* 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
@@ -1345,17 +1363,10 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (flags & ~(COPY_FR_REFLINK))
return -EINVAL;
- /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */
- ret = rw_verify_area(READ, file_in, &pos_in, len);
- if (ret >= 0)
- ret = rw_verify_area(WRITE, file_out, &pos_out, len);
- if (ret < 0)
- return ret;
-
if (!(file_in->f_mode & FMODE_READ) ||
!(file_out->f_mode & FMODE_WRITE) ||
(file_out->f_flags & O_APPEND) ||
- !file_out->f_op || !file_out->f_op->copy_file_range)
+ !file_out->f_op)
return -EBADF;
/* this could be relaxed once a method supports cross-fs copies */
@@ -1370,8 +1381,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (ret)
return ret;
- ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,
- len, flags);
+ ret = -EOPNOTSUPP;
+ 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) && !(flags & COPY_FR_REFLINK))
+ ret = vfs_copy_fr_copy(file_in, pos_in, file_out, pos_out, len);
+
if (ret > 0) {
fsnotify_access(file_in);
add_rchar(current, ret);
--
2.6.1
--
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