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Concurrent Multi-File Data Streams

In media spaces, video is often stored in a frame-per-file format.
When dealing with uncompressed realtime HD video streams in this format,
it is crucial that files do not get fragmented and that multiple files
a placed contiguously on disk.

When multiple streams are being ingested and played out at the same
time, it is critical that the filesystem does not cross the streams
and interleave them together as this creates seek and readahead
cache miss latency and prevents both ingest and playout from meeting
frame rate targets.

This patch set creates a "stream of files" concept into the allocator
to place all the data from a single stream contiguously on disk so
that RAID array readahead can be used effectively. Each additional
stream gets placed in different allocation groups within the
filesystem, thereby ensuring that we don't cross any streams. When
an AG fills up, we select a new AG for the stream that is not in
use.

The core of the functionality is the stream tracking - each inode
that we create in a directory needs to be associated with the
directories' stream. Hence every time we create a file, we look up
the directories' stream object and associate the new file with that
object.

Once we have a stream object for a file, we use the AG that the
stream object point to for allocations. If we can't allocate in that
AG (e.g. it is full) we move the entire stream to another AG. Other
inodes in the same stream are moved to the new AG on their next
allocation (i.e. lazy update).

Stream objects are kept in a cache and hold a reference on the
inode. Hence the inode cannot be reclaimed while there is an
outstanding stream reference. This means that on unlink we need to
remove the stream association and we also need to flush all the
associations on certain events that want to reclaim all unreferenced
inodes (e.g.  filesystem freeze).
Merge of xfs-linux-melb:xfs-kern:29096a by kenmcd.

  Concurrent Multi-File Data Streams feature check in.

/*
 * Copyright (c) 2001-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include <linux/sysctl.h>
#include <linux/proc_fs.h>

static struct ctl_table_header *xfs_table_header;

#ifdef CONFIG_PROC_FS
STATIC int
xfs_stats_clear_proc_handler(
	ctl_table	*ctl,
	int		write,
	struct file	*filp,
	void		__user *buffer,
	size_t		*lenp,
	loff_t		*ppos)
{
	int		c, ret, *valp = ctl->data;
	__uint32_t	vn_active;

	ret = proc_dointvec_minmax(ctl, write, filp, buffer, lenp, ppos);

	if (!ret && write && *valp) {
		printk("XFS Clearing xfsstats\n");
		for_each_possible_cpu(c) {
			preempt_disable();
			/* save vn_active, it's a universal truth! */
			vn_active = per_cpu(xfsstats, c).vn_active;
			memset(&per_cpu(xfsstats, c), 0,
			       sizeof(struct xfsstats));
			per_cpu(xfsstats, c).vn_active = vn_active;
			preempt_enable();
		}
		xfs_stats_clear = 0;
	}

	return ret;
}
#endif /* CONFIG_PROC_FS */

static ctl_table xfs_table[] = {
	{
		.ctl_name	= XFS_RESTRICT_CHOWN,
		.procname	= "restrict_chown",
		.data		= &xfs_params.restrict_chown.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.restrict_chown.min,
		.extra2		= &xfs_params.restrict_chown.max
	},
	{
		.ctl_name	= XFS_SGID_INHERIT,
		.procname	= "irix_sgid_inherit",
		.data		= &xfs_params.sgid_inherit.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.sgid_inherit.min,
		.extra2		= &xfs_params.sgid_inherit.max
	},
	{
		.ctl_name	= XFS_SYMLINK_MODE,
		.procname	= "irix_symlink_mode",
		.data		= &xfs_params.symlink_mode.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.symlink_mode.min,
		.extra2		= &xfs_params.symlink_mode.max
	},
	{
		.ctl_name	= XFS_PANIC_MASK,
		.procname	= "panic_mask",
		.data		= &xfs_params.panic_mask.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.panic_mask.min,
		.extra2		= &xfs_params.panic_mask.max
	},

	{
		.ctl_name	= XFS_ERRLEVEL,
		.procname	= "error_level",
		.data		= &xfs_params.error_level.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.error_level.min,
		.extra2		= &xfs_params.error_level.max
	},
	{
		.ctl_name	= XFS_SYNCD_TIMER,
		.procname	= "xfssyncd_centisecs",
		.data		= &xfs_params.syncd_timer.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.syncd_timer.min,
		.extra2		= &xfs_params.syncd_timer.max
	},
	{
		.ctl_name	= XFS_PROBE_DMAPI,
		.procname	= "probe_dmapi",
		.data		= &xfs_params.probe_dmapi.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.probe_dmapi.min,
		.extra2		= &xfs_params.probe_dmapi.max
	},
	{
		.ctl_name	= XFS_PROBE_IOOPS,
		.procname	= "probe_ioops",
		.data		= &xfs_params.probe_ioops.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.probe_ioops.min,
		.extra2		= &xfs_params.probe_ioops.max
	},
	{
		.ctl_name	= XFS_PROBE_QUOTA,
		.procname	= "probe_quota",
		.data		= &xfs_params.probe_quota.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.probe_quota.min,
		.extra2		= &xfs_params.probe_quota.max
	},
	{
		.ctl_name	= XFS_INHERIT_SYNC,
		.procname	= "inherit_sync",
		.data		= &xfs_params.inherit_sync.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.inherit_sync.min,
		.extra2		= &xfs_params.inherit_sync.max
	},
	{
		.ctl_name	= XFS_INHERIT_NODUMP,
		.procname	= "inherit_nodump",
		.data		= &xfs_params.inherit_nodump.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.inherit_nodump.min,
		.extra2		= &xfs_params.inherit_nodump.max
	},
	{
		.ctl_name	= XFS_INHERIT_NOATIME,
		.procname	= "inherit_noatime",
		.data		= &xfs_params.inherit_noatim.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.inherit_noatim.min,
		.extra2		= &xfs_params.inherit_noatim.max
	},
	{
		.ctl_name	= XFS_BUF_TIMER,
		.procname	= "xfsbufd_centisecs",
		.data		= &xfs_params.xfs_buf_timer.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.xfs_buf_timer.min,
		.extra2		= &xfs_params.xfs_buf_timer.max
	},
	{
		.ctl_name	= XFS_BUF_AGE,
		.procname	= "age_buffer_centisecs",
		.data		= &xfs_params.xfs_buf_age.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.xfs_buf_age.min,
		.extra2		= &xfs_params.xfs_buf_age.max
	},
	{
		.ctl_name	= XFS_INHERIT_NOSYM,
		.procname	= "inherit_nosymlinks",
		.data		= &xfs_params.inherit_nosym.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.inherit_nosym.min,
		.extra2		= &xfs_params.inherit_nosym.max
	},
	{
		.ctl_name	= XFS_ROTORSTEP,
		.procname	= "rotorstep",
		.data		= &xfs_params.rotorstep.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.rotorstep.min,
		.extra2		= &xfs_params.rotorstep.max
	},
	{
		.ctl_name	= XFS_INHERIT_NODFRG,
		.procname	= "inherit_nodefrag",
		.data		= &xfs_params.inherit_nodfrg.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.inherit_nodfrg.min,
		.extra2		= &xfs_params.inherit_nodfrg.max
	},
	{
		.ctl_name	= XFS_FILESTREAM_TIMER,
		.procname	= "filestream_centisecs",
		.data		= &xfs_params.fstrm_timer.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.fstrm_timer.min,
		.extra2		= &xfs_params.fstrm_timer.max,
	},
	/* please keep this the last entry */
#ifdef CONFIG_PROC_FS
	{
		.ctl_name	= XFS_STATS_CLEAR,
		.procname	= "stats_clear",
		.data		= &xfs_params.stats_clear.val,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &xfs_stats_clear_proc_handler,
		.strategy	= &sysctl_intvec,
		.extra1		= &xfs_params.stats_clear.min,
		.extra2		= &xfs_params.stats_clear.max
	},
#endif /* CONFIG_PROC_FS */

	{}
};

static ctl_table xfs_dir_table[] = {
	{
		.ctl_name	= FS_XFS,
		.procname	= "xfs",
		.mode		= 0555,
		.child		= xfs_table
	},
	{}
};

static ctl_table xfs_root_table[] = {
	{
		.ctl_name	= CTL_FS,
		.procname	= "fs",
		.mode		= 0555,
		.child		= xfs_dir_table
	},
	{}
};

void
xfs_sysctl_register(void)
{
	xfs_table_header = register_sysctl_table(xfs_root_table);
}

void
xfs_sysctl_unregister(void)
{
	if (xfs_table_header)
		unregister_sysctl_table(xfs_table_header);
}