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016dc8516a
Implement support for unbuffered and DIO reads in the netfs library, utilising the existing read helper code to do block splitting and individual queuing. The code also handles extraction of the destination buffer from the supplied iterator, allowing async unbuffered reads to take place. The read will be split up according to the rsize setting and, if supplied, the ->clamp_length() method. Note that the next subrequest will be issued as soon as issue_op returns, without waiting for previous ones to finish. The network filesystem needs to pause or handle queuing them if it doesn't want to fire them all at the server simultaneously. Once all the subrequests have finished, the state will be assessed and the amount of data to be indicated as having being obtained will be determined. As the subrequests may finish in any order, if an intermediate subrequest is short, any further subrequests may be copied into the buffer and then abandoned. In the future, this will also take care of doing an unbuffered read from encrypted content, with the decryption being done by the library. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org
124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Miscellaneous bits for the netfs support library.
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*
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* Copyright (C) 2022 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/module.h>
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#include <linux/export.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include "internal.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/netfs.h>
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MODULE_DESCRIPTION("Network fs support");
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MODULE_AUTHOR("Red Hat, Inc.");
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MODULE_LICENSE("GPL");
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unsigned netfs_debug;
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module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
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MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");
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#ifdef CONFIG_PROC_FS
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LIST_HEAD(netfs_io_requests);
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DEFINE_SPINLOCK(netfs_proc_lock);
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static const char *netfs_origins[nr__netfs_io_origin] = {
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[NETFS_READAHEAD] = "RA",
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[NETFS_READPAGE] = "RP",
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[NETFS_READ_FOR_WRITE] = "RW",
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[NETFS_WRITEBACK] = "WB",
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[NETFS_DIO_READ] = "DR",
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};
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/*
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* Generate a list of I/O requests in /proc/fs/netfs/requests
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*/
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static int netfs_requests_seq_show(struct seq_file *m, void *v)
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{
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struct netfs_io_request *rreq;
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if (v == &netfs_io_requests) {
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seq_puts(m,
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"REQUEST OR REF FL ERR OPS COVERAGE\n"
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"======== == === == ==== === =========\n"
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);
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return 0;
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}
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rreq = list_entry(v, struct netfs_io_request, proc_link);
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seq_printf(m,
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"%08x %s %3d %2lx %4d %3d @%04llx %zx/%zx",
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rreq->debug_id,
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netfs_origins[rreq->origin],
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refcount_read(&rreq->ref),
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rreq->flags,
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rreq->error,
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atomic_read(&rreq->nr_outstanding),
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rreq->start, rreq->submitted, rreq->len);
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seq_putc(m, '\n');
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return 0;
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}
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static void *netfs_requests_seq_start(struct seq_file *m, loff_t *_pos)
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__acquires(rcu)
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{
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rcu_read_lock();
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return seq_list_start_head(&netfs_io_requests, *_pos);
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}
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static void *netfs_requests_seq_next(struct seq_file *m, void *v, loff_t *_pos)
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{
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return seq_list_next(v, &netfs_io_requests, _pos);
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}
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static void netfs_requests_seq_stop(struct seq_file *m, void *v)
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__releases(rcu)
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{
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rcu_read_unlock();
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}
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static const struct seq_operations netfs_requests_seq_ops = {
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.start = netfs_requests_seq_start,
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.next = netfs_requests_seq_next,
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.stop = netfs_requests_seq_stop,
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.show = netfs_requests_seq_show,
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};
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#endif /* CONFIG_PROC_FS */
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static int __init netfs_init(void)
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{
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int ret = -ENOMEM;
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if (!proc_mkdir("fs/netfs", NULL))
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goto error;
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if (!proc_create_seq("fs/netfs/requests", S_IFREG | 0444, NULL,
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&netfs_requests_seq_ops))
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goto error_proc;
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#ifdef CONFIG_FSCACHE_STATS
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if (!proc_create_single("fs/netfs/stats", S_IFREG | 0444, NULL,
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netfs_stats_show))
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goto error_proc;
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#endif
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ret = fscache_init();
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if (ret < 0)
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goto error_proc;
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return 0;
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error_proc:
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remove_proc_entry("fs/netfs", NULL);
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error:
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return ret;
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}
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fs_initcall(netfs_init);
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static void __exit netfs_exit(void)
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{
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fscache_exit();
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remove_proc_entry("fs/netfs", NULL);
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}
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module_exit(netfs_exit);
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