[11/14] fs: implement kernel_read using __kernel_read
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Message ID 20200624161335.1810359-12-hch@lst.de
State New
Headers show
Series
  • [01/14] cachefiles: switch to kernel_write
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Commit Message

Christoph Hellwig June 24, 2020, 4:13 p.m. UTC
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(-)

Patch
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diff --git a/fs/read_write.c b/fs/read_write.c
index cc8e0b4f3cd697..a0a0b5d1d9249c 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -455,15 +455,12 @@  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);