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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 18:50:03 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 18:50:03 +0000 |
commit | 01a69402cf9d38ff180345d55c2ee51c7e89fbc7 (patch) | |
tree | b406c5242a088c4f59c6e4b719b783f43aca6ae9 /fs/netfs/direct_read.c | |
parent | Adding upstream version 6.7.12. (diff) | |
download | linux-upstream/6.8.9.tar.xz linux-upstream/6.8.9.zip |
Adding upstream version 6.8.9.upstream/6.8.9
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/netfs/direct_read.c')
-rw-r--r-- | fs/netfs/direct_read.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c new file mode 100644 index 0000000000..ad4370b393 --- /dev/null +++ b/fs/netfs/direct_read.c @@ -0,0 +1,125 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Direct I/O support. + * + * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/export.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/slab.h> +#include <linux/uio.h> +#include <linux/sched/mm.h> +#include <linux/task_io_accounting_ops.h> +#include <linux/netfs.h> +#include "internal.h" + +/** + * netfs_unbuffered_read_iter_locked - Perform an unbuffered or direct I/O read + * @iocb: The I/O control descriptor describing the read + * @iter: The output buffer (also specifies read length) + * + * Perform an unbuffered I/O or direct I/O from the file in @iocb to the + * output buffer. No use is made of the pagecache. + * + * The caller must hold any appropriate locks. + */ +static ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter) +{ + struct netfs_io_request *rreq; + ssize_t ret; + size_t orig_count = iov_iter_count(iter); + bool async = !is_sync_kiocb(iocb); + + _enter(""); + + if (!orig_count) + return 0; /* Don't update atime */ + + ret = kiocb_write_and_wait(iocb, orig_count); + if (ret < 0) + return ret; + file_accessed(iocb->ki_filp); + + rreq = netfs_alloc_request(iocb->ki_filp->f_mapping, iocb->ki_filp, + iocb->ki_pos, orig_count, + NETFS_DIO_READ); + if (IS_ERR(rreq)) + return PTR_ERR(rreq); + + netfs_stat(&netfs_n_rh_dio_read); + trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_dio_read); + + /* If this is an async op, we have to keep track of the destination + * buffer for ourselves as the caller's iterator will be trashed when + * we return. + * + * In such a case, extract an iterator to represent as much of the the + * output buffer as we can manage. Note that the extraction might not + * be able to allocate a sufficiently large bvec array and may shorten + * the request. + */ + if (user_backed_iter(iter)) { + ret = netfs_extract_user_iter(iter, rreq->len, &rreq->iter, 0); + if (ret < 0) + goto out; + rreq->direct_bv = (struct bio_vec *)rreq->iter.bvec; + rreq->direct_bv_count = ret; + rreq->direct_bv_unpin = iov_iter_extract_will_pin(iter); + rreq->len = iov_iter_count(&rreq->iter); + } else { + rreq->iter = *iter; + rreq->len = orig_count; + rreq->direct_bv_unpin = false; + iov_iter_advance(iter, orig_count); + } + + // TODO: Set up bounce buffer if needed + + if (async) + rreq->iocb = iocb; + + ret = netfs_begin_read(rreq, is_sync_kiocb(iocb)); + if (ret < 0) + goto out; /* May be -EIOCBQUEUED */ + if (!async) { + // TODO: Copy from bounce buffer + iocb->ki_pos += rreq->transferred; + ret = rreq->transferred; + } + +out: + netfs_put_request(rreq, false, netfs_rreq_trace_put_return); + if (ret > 0) + orig_count -= ret; + if (ret != -EIOCBQUEUED) + iov_iter_revert(iter, orig_count - iov_iter_count(iter)); + return ret; +} + +/** + * netfs_unbuffered_read_iter - Perform an unbuffered or direct I/O read + * @iocb: The I/O control descriptor describing the read + * @iter: The output buffer (also specifies read length) + * + * Perform an unbuffered I/O or direct I/O from the file in @iocb to the + * output buffer. No use is made of the pagecache. + */ +ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter) +{ + struct inode *inode = file_inode(iocb->ki_filp); + ssize_t ret; + + if (!iter->count) + return 0; /* Don't update atime */ + + ret = netfs_start_io_direct(inode); + if (ret == 0) { + ret = netfs_unbuffered_read_iter_locked(iocb, iter); + netfs_end_io_direct(inode); + } + return ret; +} +EXPORT_SYMBOL(netfs_unbuffered_read_iter); |