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authorDarrick J. Wong <darrick.wong@oracle.com>2018-10-30 02:41:49 +0300
committerDave Chinner <david@fromorbit.com>2018-10-30 02:41:49 +0300
commit42ec3d4c02187a18e27ff94b409ec27234bf2ffd (patch)
treec9db04db8187c370718a43e6067af0e5aa944500 /Documentation
parent8dde90bca6fca3736ea20109654bcf6dcf2ecf1d (diff)
downloadlinux-42ec3d4c02187a18e27ff94b409ec27234bf2ffd.tar.xz
vfs: make remap_file_range functions take and return bytes completed
Change the remap_file_range functions to take a number of bytes to operate upon and return the number of bytes they operated on. This is a requirement for allowing fs implementations to return short clone/dedupe results to the user, which will enable us to obey resource limits in a graceful manner. A subsequent patch will enable copy_file_range to signal to the ->clone_file_range implementation that it can handle a short length, which will be returned in the function's return value. For now the short return is not implemented anywhere so the behavior won't change -- either copy_file_range manages to clone the entire range or it tries an alternative. Neither clone ioctl can take advantage of this, alas. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/vfs.txt10
1 files changed, 5 insertions, 5 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 6f5babfee27b..1bd2919deaca 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -883,9 +883,9 @@ struct file_operations {
unsigned (*mmap_capabilities)(struct file *);
#endif
ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);
- int (*remap_file_range)(struct file *file_in, loff_t pos_in,
- struct file *file_out, loff_t pos_out,
- u64 len, unsigned int remap_flags);
+ loff_t (*remap_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);
int (*fadvise)(struct file *, loff_t, loff_t, int);
};
@@ -966,8 +966,8 @@ otherwise noted.
implementation should remap len bytes at pos_in of the source file into
the dest file at pos_out. Implementations must handle callers passing
in len == 0; this means "remap to the end of the source file". The
- return value should be zero if all bytes were remapped, or the usual
- negative error code if the remapping did not succeed completely.
+ return value should the number of bytes remapped, or the usual
+ negative error code if errors occurred before any bytes were remapped.
The remap_flags parameter accepts REMAP_FILE_* flags. If
REMAP_FILE_DEDUP is set then the implementation must only remap if the
requested file ranges have identical contents.