If flags includes COPY_FILE_RANGE_FILESIZE then the length copied is the length of the file. off_in and off_out are ignored. len must be 0 or the file size.
This implementation saves a call to stat() in the common case of copying files. It does not fix any race conditions, but that is possible in the future with this interface. EAGAIN: If COPY_FILE_RANGE_FILESIZE was passed and len is not 0 or the file size. Signed-off-by: Shawn Landden <[email protected]> CC: <[email protected]> --- fs/read_write.c | 14 +++++++++++++- include/uapi/linux/stat.h | 4 ++++ 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/fs/read_write.c b/fs/read_write.c index 61b43ad7608e..6d06361f0856 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1557,7 +1557,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, struct inode *inode_out = file_inode(file_out); ssize_t ret; - if (flags != 0) + if ((flags & ~COPY_FILE_RANGE_FILESIZE) != 0) return -EINVAL; if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode)) @@ -1565,6 +1565,18 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode)) return -EINVAL; + if (flags & COPY_FILE_RANGE_FILESIZE) { + struct kstat stat; + int error; + error = vfs_getattr(&file_in->f_path, &stat, + STATX_SIZE, 0); + if (error < 0) + return error; + if (!(len == 0 || len == stat.size)) + return -EAGAIN; + len = stat.size; + } + ret = rw_verify_area(READ, file_in, &pos_in, len); if (unlikely(ret)) return ret; diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h index 7b35e98d3c58..1075aa4666ef 100644 --- a/include/uapi/linux/stat.h +++ b/include/uapi/linux/stat.h @@ -170,5 +170,9 @@ struct statx { #define STATX_ATTR_AUTOMOUNT 0x00001000 /* Dir: Automount trigger */ +/* + * Flags for copy_file_range() + */ +#define COPY_FILE_RANGE_FILESIZE 0x00000001 /* Copy the full length of the input file */ #endif /* _UAPI_LINUX_STAT_H */ -- 2.20.1
