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Subject[PATCH 12/14] fs: implement kernel_read using __kernel_read
Date
Consolidate the two in-kernel read helpers to make upcoming changes
easier. The only difference are the missing call to rw_verify_area
in kernel_read, and an access_ok check that doesn't make sense for
kernel buffers to start with.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/read_write.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index bd12af8a895c8..4e19152a7efe0 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -453,15 +453,12 @@ ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)

ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
{
- mm_segment_t old_fs;
- ssize_t result;
+ ssize_t ret;

- old_fs = get_fs();
- set_fs(KERNEL_DS);
- /* The cast to a user pointer is valid due to the set_fs() */
- result = vfs_read(file, (void __user *)buf, count, pos);
- set_fs(old_fs);
- return result;
+ ret = rw_verify_area(READ, file, pos, count);
+ if (ret)
+ return ret;
+ return __kernel_read(file, buf, count, pos);
}
EXPORT_SYMBOL(kernel_read);

--
2.26.2
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