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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
 */
#ifndef __XFS_SYSCTL_H__
#define __XFS_SYSCTL_H__

#include <linux/sysctl.h>

/*
 * Tunable xfs parameters
 */

typedef struct xfs_sysctl_val {
	int min;
	int val;
	int max;
} xfs_sysctl_val_t;

typedef struct xfs_param {
	xfs_sysctl_val_t restrict_chown;/* Root/non-root can give away files.*/
	xfs_sysctl_val_t sgid_inherit;	/* Inherit S_ISGID if process' GID is
					 * not a member of parent dir GID. */
	xfs_sysctl_val_t symlink_mode;	/* Link creat mode affected by umask */
	xfs_sysctl_val_t panic_mask;	/* bitmask to cause panic on errors. */
	xfs_sysctl_val_t error_level;	/* Degree of reporting for problems  */
	xfs_sysctl_val_t syncd_timer;	/* Interval between xfssyncd wakeups */
	xfs_sysctl_val_t stats_clear;	/* Reset all XFS statistics to zero. */
	xfs_sysctl_val_t probe_dmapi;	/* probe for DMAPI module on mount. */
	xfs_sysctl_val_t probe_ioops;	/* probe for an IO module on mount. */
	xfs_sysctl_val_t probe_quota;	/* probe for quota module on mount. */
	xfs_sysctl_val_t inherit_sync;	/* Inherit the "sync" inode flag. */
	xfs_sysctl_val_t inherit_nodump;/* Inherit the "nodump" inode flag. */
	xfs_sysctl_val_t inherit_noatim;/* Inherit the "noatime" inode flag. */
	xfs_sysctl_val_t xfs_buf_timer;	/* Interval between xfsbufd wakeups. */
	xfs_sysctl_val_t xfs_buf_age;	/* Metadata buffer age before flush. */
	xfs_sysctl_val_t inherit_nosym;	/* Inherit the "nosymlinks" flag. */
	xfs_sysctl_val_t rotorstep;	/* inode32 AG rotoring control knob */
	xfs_sysctl_val_t inherit_nodfrg;/* Inherit the "nodefrag" inode flag. */
	xfs_sysctl_val_t fstrm_timer;	/* Filestream dir-AG assoc'n timeout. */
} xfs_param_t;

/*
 * xfs_error_level:
 *
 * How much error reporting will be done when internal problems are
 * encountered.  These problems normally return an EFSCORRUPTED to their
 * caller, with no other information reported.
 *
 * 0	No error reports
 * 1	Report EFSCORRUPTED errors that will cause a filesystem shutdown
 * 5	Report all EFSCORRUPTED errors (all of the above errors, plus any
 *	additional errors that are known to not cause shutdowns)
 *
 * xfs_panic_mask bit 0x8 turns the error reports into panics
 */

enum {
	/* XFS_REFCACHE_SIZE = 1 */
	/* XFS_REFCACHE_PURGE = 2 */
	XFS_RESTRICT_CHOWN = 3,
	XFS_SGID_INHERIT = 4,
	XFS_SYMLINK_MODE = 5,
	XFS_PANIC_MASK = 6,
	XFS_ERRLEVEL = 7,
	XFS_SYNCD_TIMER = 8,
	XFS_PROBE_DMAPI = 9,
	XFS_PROBE_IOOPS = 10,
	XFS_PROBE_QUOTA = 11,
	XFS_STATS_CLEAR = 12,
	XFS_INHERIT_SYNC = 13,
	XFS_INHERIT_NODUMP = 14,
	XFS_INHERIT_NOATIME = 15,
	XFS_BUF_TIMER = 16,
	XFS_BUF_AGE = 17,
	/* XFS_IO_BYPASS = 18 */
	XFS_INHERIT_NOSYM = 19,
	XFS_ROTORSTEP = 20,
	XFS_INHERIT_NODFRG = 21,
	XFS_FILESTREAM_TIMER = 22,
};

extern xfs_param_t	xfs_params;

#ifdef CONFIG_SYSCTL
extern void xfs_sysctl_register(void);
extern void xfs_sysctl_unregister(void);
#else
# define xfs_sysctl_register()		do { } while (0)
# define xfs_sysctl_unregister()	do { } while (0)
#endif /* CONFIG_SYSCTL */

#endif /* __XFS_SYSCTL_H__ */