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fs: update atime before I/O in generic_file_read_iter 

After the call to ->direct_IO the final reference to the file might have
been dropped by aio_complete already, and the call to file_accessed might
cause a use after free.

Instead update the access time before the I/O, similar to how we
update the time stamps before writes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Christoph Hellwig 2016-10-03 09:48:08 +11:00 committed by Dave Chinner
parent a447d7cd15
commit 0d5b0cf246
1 changed files with 7 additions and 7 deletions
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14
mm/filemap.c
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@ -1910,16 +1910,18 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
if (iocb->ki_flags & IOCB_DIRECT) {
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
struct iov_iter data = *iter;
loff_t size;
size = i_size_read(inode);
retval = filemap_write_and_wait_range(mapping, iocb->ki_pos,
iocb->ki_pos + count - 1);
if (!retval) {
struct iov_iter data = *iter;
retval = mapping->a_ops->direct_IO(iocb, &data);
}
if (retval < 0)
goto out;
file_accessed(file);
retval = mapping->a_ops->direct_IO(iocb, &data);
if (retval > 0) {
iocb->ki_pos += retval;
iov_iter_advance(iter, retval);
@ -1935,10 +1937,8 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
* DAX files, so don't bother trying.
*/
if (retval < 0 || !iov_iter_count(iter) || iocb->ki_pos >= size ||
IS_DAX(inode)) {
file_accessed(file);
IS_DAX(inode))
goto out;
}
}
retval = do_generic_file_read(file, &iocb->ki_pos, iter, retval);