[1/1] man-page: copy_file_range(2) allow for cross-device copies

Message ID 20181030205614.40754-3-olga.kornievskaia@gmail.com
State New
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  • [1/1] man-page: copy_file_range(2) allow for cross-device copies
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Commit Message

Olga Kornievskaia Oct. 30, 2018, 8:56 p.m.
From: Olga Kornievskaia <kolga@netapp.com>

A proposed VFS change removes the check for the files to reside
under the same file system prior to attempting a copy. Instead,
a file system driver implementation of the destination file
is allowed to perform a cross-device copy_file_range(). If
that filesystem does not support cross device copy, it returns

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
 man2/copy_file_range.2 | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)


diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2
index 20374ab..03750c5 100644
--- a/man2/copy_file_range.2
+++ b/man2/copy_file_range.2
@@ -39,7 +39,8 @@  The
 .BR copy_file_range ()
 system call performs an in-kernel copy between two file descriptors
 without the additional cost of transferring data from the kernel to user space
-and then back into the kernel.
+and then back into the kernel. Starting kernel version 4.21 passed in
+file descriptors are not required to be under the same mounted file system.
 It copies up to
 .I len
 bytes of data from file descriptor
@@ -129,9 +130,9 @@  Out of memory.
 There is not enough space on the target filesystem to complete the copy.
-The files referred to by
-.IR file_in " and " file_out
-are not on the same mounted filesystem.
+The file system of the 
+.I file_out
+does not support cross device file copy.
 .BR copy_file_range ()