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fs: implement kernel_read using __kernel_read

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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>
This commit is contained in:
Christoph Hellwig
2020-05-08 09:00:28 +02:00
parent a1f9b1c043
commit 6209dd9132
1 changed files with 5 additions and 8 deletions
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13
fs/read_write.c
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@@ -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);