From: Shawn Landden <shawn@git.icu>
To: unlisted-recipients:; (no To-header on input)
Cc: linux-api@vger.kernel.org, linux-dev@vger.kernel.org,
linux-fsdevel@vger.kernel.org,
Andy Lutomirski <luto@amacapital.net>,
Shawn Landden <shawn@git.icu>
Subject: [PATCH] new flag COPY_FILE_RANGE_FILESIZE for copy_file_range()
Date: Sat, 13 Apr 2019 19:25:19 -0500 [thread overview]
Message-ID: <20190414002519.24991-1-shawn@git.icu> (raw)
In-Reply-To: <20190413204947.9394-1-shawn@git.icu>
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.
This implementation saves a call to stat() in the common case
of copying files. It does not fix any race conditions.
EINVAL: If COPY_FILE_RANGE_FILESIZE was passed and len is not 0.
Signed-off-by: Shawn Landden <shawn@git.icu>
CC: <linux-api@vger.kernel.org>
v2: do not accept len == size.
---
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..f5862849bff7 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;
+ if (len != 0)
+ return -EINVAL;
+ error = vfs_getattr(&file_in->f_path, &stat,
+ STATX_SIZE, 0);
+ if (error < 0)
+ return error;
+ 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
next prev parent reply other threads:[~2019-04-14 0:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-13 20:49 [PATCH] new flag COPY_FILE_RANGE_FILESIZE for copy_file_range() Shawn Landden
2019-04-13 21:48 ` Andy Lutomirski
2019-04-14 0:25 ` Shawn Landden [this message]
2019-04-13 20:54 Shawn Landden
2019-04-14 1:02 ` Darrick J. Wong
2019-04-14 7:10 ` Amir Goldstein
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