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14b1cd2534
Fix to take the i_rwsem (through the netfs locking wrappers) before taking
cinode->lock_sem.
Fixes: 3ee1a1fc39 ("cifs: Cut over to using netfslib")
Reported-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
127 lines
3.5 KiB
C
127 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Direct I/O support.
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*
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* Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/export.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/slab.h>
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#include <linux/uio.h>
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#include <linux/sched/mm.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/netfs.h>
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#include "internal.h"
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/**
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* netfs_unbuffered_read_iter_locked - Perform an unbuffered or direct I/O read
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* @iocb: The I/O control descriptor describing the read
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* @iter: The output buffer (also specifies read length)
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*
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* Perform an unbuffered I/O or direct I/O from the file in @iocb to the
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* output buffer. No use is made of the pagecache.
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*
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* The caller must hold any appropriate locks.
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*/
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ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter)
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{
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struct netfs_io_request *rreq;
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ssize_t ret;
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size_t orig_count = iov_iter_count(iter);
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bool async = !is_sync_kiocb(iocb);
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_enter("");
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if (!orig_count)
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return 0; /* Don't update atime */
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ret = kiocb_write_and_wait(iocb, orig_count);
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if (ret < 0)
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return ret;
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file_accessed(iocb->ki_filp);
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rreq = netfs_alloc_request(iocb->ki_filp->f_mapping, iocb->ki_filp,
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iocb->ki_pos, orig_count,
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NETFS_DIO_READ);
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if (IS_ERR(rreq))
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return PTR_ERR(rreq);
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netfs_stat(&netfs_n_rh_dio_read);
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trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_dio_read);
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/* If this is an async op, we have to keep track of the destination
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* buffer for ourselves as the caller's iterator will be trashed when
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* we return.
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*
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* In such a case, extract an iterator to represent as much of the the
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* output buffer as we can manage. Note that the extraction might not
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* be able to allocate a sufficiently large bvec array and may shorten
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* the request.
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*/
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if (user_backed_iter(iter)) {
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ret = netfs_extract_user_iter(iter, rreq->len, &rreq->iter, 0);
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if (ret < 0)
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goto out;
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rreq->direct_bv = (struct bio_vec *)rreq->iter.bvec;
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rreq->direct_bv_count = ret;
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rreq->direct_bv_unpin = iov_iter_extract_will_pin(iter);
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rreq->len = iov_iter_count(&rreq->iter);
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} else {
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rreq->iter = *iter;
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rreq->len = orig_count;
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rreq->direct_bv_unpin = false;
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iov_iter_advance(iter, orig_count);
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}
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// TODO: Set up bounce buffer if needed
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if (async)
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rreq->iocb = iocb;
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ret = netfs_begin_read(rreq, is_sync_kiocb(iocb));
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if (ret < 0)
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goto out; /* May be -EIOCBQUEUED */
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if (!async) {
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// TODO: Copy from bounce buffer
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iocb->ki_pos += rreq->transferred;
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ret = rreq->transferred;
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}
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out:
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netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
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if (ret > 0)
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orig_count -= ret;
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if (ret != -EIOCBQUEUED)
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iov_iter_revert(iter, orig_count - iov_iter_count(iter));
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return ret;
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}
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EXPORT_SYMBOL(netfs_unbuffered_read_iter_locked);
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/**
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* netfs_unbuffered_read_iter - Perform an unbuffered or direct I/O read
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* @iocb: The I/O control descriptor describing the read
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* @iter: The output buffer (also specifies read length)
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*
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* Perform an unbuffered I/O or direct I/O from the file in @iocb to the
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* output buffer. No use is made of the pagecache.
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*/
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ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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struct inode *inode = file_inode(iocb->ki_filp);
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ssize_t ret;
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if (!iter->count)
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return 0; /* Don't update atime */
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ret = netfs_start_io_direct(inode);
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if (ret == 0) {
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ret = netfs_unbuffered_read_iter_locked(iocb, iter);
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netfs_end_io_direct(inode);
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}
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return ret;
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}
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EXPORT_SYMBOL(netfs_unbuffered_read_iter);
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