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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) 2000-2005 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_CLNT_H__
#define __XFS_CLNT_H__

/*
 * XFS arguments structure, constructed from the arguments we
 * are passed via the mount system call.
 *
 * NOTE: The mount system call is handled differently between
 * Linux and IRIX.  In IRIX we worked work with a binary data
 * structure coming in across the syscall interface from user
 * space (the mount userspace knows about each filesystem type
 * and the set of valid options for it, and converts the users
 * argument string into a binary structure _before_ making the
 * system call), and the ABI issues that this implies.
 *
 * In Linux, we are passed a comma separated set of options;
 * ie. a NULL terminated string of characters.  Userspace mount
 * code does not have any knowledge of mount options expected by
 * each filesystem type and so each filesystem parses its mount
 * options in kernel space.
 *
 * For the Linux port, we kept this structure pretty much intact
 * and use it internally (because the existing code groks it).
 */
struct xfs_mount_args {
	int	flags;		/* flags -> see XFSMNT_... macros below */
	int	flags2;		/* flags -> see XFSMNT2_... macros below */
	int	logbufs;	/* Number of log buffers, -1 to default */
	int	logbufsize;	/* Size of log buffers, -1 to default */
	char	fsname[MAXNAMELEN+1];	/* data device name */
	char	rtname[MAXNAMELEN+1];	/* realtime device filename */
	char	logname[MAXNAMELEN+1];	/* journal device filename */
	char	mtpt[MAXNAMELEN+1];	/* filesystem mount point */
	int	sunit;		/* stripe unit (BBs) */
	int	swidth;		/* stripe width (BBs), multiple of sunit */
	uchar_t iosizelog;	/* log2 of the preferred I/O size */
	int	ihashsize;	/* inode hash table size (buckets) */
};

/*
 * XFS mount option flags -- args->flags1
 */
#define	XFSMNT_ATTR2		0x00000001	/* allow ATTR2 EA format */
#define	XFSMNT_WSYNC		0x00000002	/* safe mode nfs mount
						 * compatible */
#define	XFSMNT_INO64		0x00000004	/* move inode numbers up
						 * past 2^32 */
#define XFSMNT_UQUOTA		0x00000008	/* user quota accounting */
#define XFSMNT_PQUOTA		0x00000010	/* IRIX prj quota accounting */
#define XFSMNT_UQUOTAENF	0x00000020	/* user quota limit
						 * enforcement */
#define XFSMNT_PQUOTAENF	0x00000040	/* IRIX project quota limit
						 * enforcement */
#define XFSMNT_QUIET		0x00000080	/* don't report mount errors */
#define XFSMNT_NOALIGN		0x00000200	/* don't allocate at
						 * stripe boundaries*/
#define XFSMNT_RETERR		0x00000400	/* return error to user */
#define XFSMNT_NORECOVERY	0x00000800	/* no recovery, implies
						 * read-only mount */
#define XFSMNT_SHARED		0x00001000	/* shared XFS mount */
#define XFSMNT_IOSIZE		0x00002000	/* optimize for I/O size */
#define XFSMNT_OSYNCISOSYNC	0x00004000	/* o_sync is REALLY o_sync */
						/* (osyncisdsync is default) */
#define XFSMNT_32BITINODES	0x00200000	/* restrict inodes to 32
						 * bits of address space */
#define XFSMNT_GQUOTA		0x00400000	/* group quota accounting */
#define XFSMNT_GQUOTAENF	0x00800000	/* group quota limit
						 * enforcement */
#define XFSMNT_NOUUID		0x01000000	/* Ignore fs uuid */
#define XFSMNT_DMAPI		0x02000000	/* enable dmapi/xdsm */
#define XFSMNT_BARRIER		0x04000000	/* use write barriers */
#define XFSMNT_IDELETE		0x08000000	/* inode cluster delete */
#define XFSMNT_SWALLOC		0x10000000	/* turn on stripe width
						 * allocation */
#define XFSMNT_IHASHSIZE	0x20000000	/* inode hash table size */
#define XFSMNT_DIRSYNC		0x40000000	/* sync creat,link,unlink,rename
						 * symlink,mkdir,rmdir,mknod */
#define XFSMNT_FLAGS2		0x80000000	/* more flags set in flags2 */

/*
 * XFS mount option flags -- args->flags2
 */
#define XFSMNT2_COMPAT_IOSIZE	0x00000001	/* don't report large preferred
						 * I/O size in stat(2) */
#define XFSMNT2_FILESTREAMS	0x00000002	/* enable the filestreams
						 * allocator */

#endif	/* __XFS_CLNT_H__ */