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remarkable-linux/fs/xfs/xfs_ag.h
David Chinner 2a82b8be8a [XFS] 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).

SGI-PV: 964469
SGI-Modid: xfs-linux-melb:xfs-kern:29096a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: Vlad Apostolov <vapo@sgi.com>
2007-07-14 15:40:53 +10:00

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/*
* Copyright (c) 2000-2003,2005 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_AG_H__
#define __XFS_AG_H__
/*
* Allocation group header
* This is divided into three structures, placed in sequential 512-byte
* buffers after a copy of the superblock (also in a 512-byte buffer).
*/
struct xfs_buf;
struct xfs_mount;
struct xfs_trans;
#define XFS_AGF_MAGIC 0x58414746 /* 'XAGF' */
#define XFS_AGI_MAGIC 0x58414749 /* 'XAGI' */
#define XFS_AGF_VERSION 1
#define XFS_AGI_VERSION 1
#define XFS_AGF_GOOD_VERSION(v) ((v) == XFS_AGF_VERSION)
#define XFS_AGI_GOOD_VERSION(v) ((v) == XFS_AGI_VERSION)
/*
* Btree number 0 is bno, 1 is cnt. This value gives the size of the
* arrays below.
*/
#define XFS_BTNUM_AGF ((int)XFS_BTNUM_CNTi + 1)
/*
* The second word of agf_levels in the first a.g. overlaps the EFS
* superblock's magic number. Since the magic numbers valid for EFS
* are > 64k, our value cannot be confused for an EFS superblock's.
*/
typedef struct xfs_agf {
/*
* Common allocation group header information
*/
__be32 agf_magicnum; /* magic number == XFS_AGF_MAGIC */
__be32 agf_versionnum; /* header version == XFS_AGF_VERSION */
__be32 agf_seqno; /* sequence # starting from 0 */
__be32 agf_length; /* size in blocks of a.g. */
/*
* Freespace information
*/
__be32 agf_roots[XFS_BTNUM_AGF]; /* root blocks */
__be32 agf_spare0; /* spare field */
__be32 agf_levels[XFS_BTNUM_AGF]; /* btree levels */
__be32 agf_spare1; /* spare field */
__be32 agf_flfirst; /* first freelist block's index */
__be32 agf_fllast; /* last freelist block's index */
__be32 agf_flcount; /* count of blocks in freelist */
__be32 agf_freeblks; /* total free blocks */
__be32 agf_longest; /* longest free space */
__be32 agf_btreeblks; /* # of blocks held in AGF btrees */
} xfs_agf_t;
#define XFS_AGF_MAGICNUM 0x00000001
#define XFS_AGF_VERSIONNUM 0x00000002
#define XFS_AGF_SEQNO 0x00000004
#define XFS_AGF_LENGTH 0x00000008
#define XFS_AGF_ROOTS 0x00000010
#define XFS_AGF_LEVELS 0x00000020
#define XFS_AGF_FLFIRST 0x00000040
#define XFS_AGF_FLLAST 0x00000080
#define XFS_AGF_FLCOUNT 0x00000100
#define XFS_AGF_FREEBLKS 0x00000200
#define XFS_AGF_LONGEST 0x00000400
#define XFS_AGF_BTREEBLKS 0x00000800
#define XFS_AGF_NUM_BITS 12
#define XFS_AGF_ALL_BITS ((1 << XFS_AGF_NUM_BITS) - 1)
/* disk block (xfs_daddr_t) in the AG */
#define XFS_AGF_DADDR(mp) ((xfs_daddr_t)(1 << (mp)->m_sectbb_log))
#define XFS_AGF_BLOCK(mp) XFS_HDR_BLOCK(mp, XFS_AGF_DADDR(mp))
#define XFS_BUF_TO_AGF(bp) ((xfs_agf_t *)XFS_BUF_PTR(bp))
/*
* Size of the unlinked inode hash table in the agi.
*/
#define XFS_AGI_UNLINKED_BUCKETS 64
typedef struct xfs_agi {
/*
* Common allocation group header information
*/
__be32 agi_magicnum; /* magic number == XFS_AGI_MAGIC */
__be32 agi_versionnum; /* header version == XFS_AGI_VERSION */
__be32 agi_seqno; /* sequence # starting from 0 */
__be32 agi_length; /* size in blocks of a.g. */
/*
* Inode information
* Inodes are mapped by interpreting the inode number, so no
* mapping data is needed here.
*/
__be32 agi_count; /* count of allocated inodes */
__be32 agi_root; /* root of inode btree */
__be32 agi_level; /* levels in inode btree */
__be32 agi_freecount; /* number of free inodes */
__be32 agi_newino; /* new inode just allocated */
__be32 agi_dirino; /* last directory inode chunk */
/*
* Hash table of inodes which have been unlinked but are
* still being referenced.
*/
__be32 agi_unlinked[XFS_AGI_UNLINKED_BUCKETS];
} xfs_agi_t;
#define XFS_AGI_MAGICNUM 0x00000001
#define XFS_AGI_VERSIONNUM 0x00000002
#define XFS_AGI_SEQNO 0x00000004
#define XFS_AGI_LENGTH 0x00000008
#define XFS_AGI_COUNT 0x00000010
#define XFS_AGI_ROOT 0x00000020
#define XFS_AGI_LEVEL 0x00000040
#define XFS_AGI_FREECOUNT 0x00000080
#define XFS_AGI_NEWINO 0x00000100
#define XFS_AGI_DIRINO 0x00000200
#define XFS_AGI_UNLINKED 0x00000400
#define XFS_AGI_NUM_BITS 11
#define XFS_AGI_ALL_BITS ((1 << XFS_AGI_NUM_BITS) - 1)
/* disk block (xfs_daddr_t) in the AG */
#define XFS_AGI_DADDR(mp) ((xfs_daddr_t)(2 << (mp)->m_sectbb_log))
#define XFS_AGI_BLOCK(mp) XFS_HDR_BLOCK(mp, XFS_AGI_DADDR(mp))
#define XFS_BUF_TO_AGI(bp) ((xfs_agi_t *)XFS_BUF_PTR(bp))
/*
* The third a.g. block contains the a.g. freelist, an array
* of block pointers to blocks owned by the allocation btree code.
*/
#define XFS_AGFL_DADDR(mp) ((xfs_daddr_t)(3 << (mp)->m_sectbb_log))
#define XFS_AGFL_BLOCK(mp) XFS_HDR_BLOCK(mp, XFS_AGFL_DADDR(mp))
#define XFS_AGFL_SIZE(mp) ((mp)->m_sb.sb_sectsize / sizeof(xfs_agblock_t))
#define XFS_BUF_TO_AGFL(bp) ((xfs_agfl_t *)XFS_BUF_PTR(bp))
typedef struct xfs_agfl {
__be32 agfl_bno[1]; /* actually XFS_AGFL_SIZE(mp) */
} xfs_agfl_t;
/*
* Busy block/extent entry. Used in perag to mark blocks that have been freed
* but whose transactions aren't committed to disk yet.
*/
typedef struct xfs_perag_busy {
xfs_agblock_t busy_start;
xfs_extlen_t busy_length;
struct xfs_trans *busy_tp; /* transaction that did the free */
} xfs_perag_busy_t;
/*
* Per-ag incore structure, copies of information in agf and agi,
* to improve the performance of allocation group selection.
*
* pick sizes which fit in allocation buckets well
*/
#if (BITS_PER_LONG == 32)
#define XFS_PAGB_NUM_SLOTS 84
#elif (BITS_PER_LONG == 64)
#define XFS_PAGB_NUM_SLOTS 128
#endif
typedef struct xfs_perag
{
char pagf_init; /* this agf's entry is initialized */
char pagi_init; /* this agi's entry is initialized */
char pagf_metadata; /* the agf is preferred to be metadata */
char pagi_inodeok; /* The agi is ok for inodes */
__uint8_t pagf_levels[XFS_BTNUM_AGF];
/* # of levels in bno & cnt btree */
__uint32_t pagf_flcount; /* count of blocks in freelist */
xfs_extlen_t pagf_freeblks; /* total free blocks */
xfs_extlen_t pagf_longest; /* longest free space */
__uint32_t pagf_btreeblks; /* # of blocks held in AGF btrees */
xfs_agino_t pagi_freecount; /* number of free inodes */
xfs_agino_t pagi_count; /* number of allocated inodes */
int pagb_count; /* pagb slots in use */
#ifdef __KERNEL__
lock_t pagb_lock; /* lock for pagb_list */
#endif
xfs_perag_busy_t *pagb_list; /* unstable blocks */
atomic_t pagf_fstrms; /* # of filestreams active in this AG */
} xfs_perag_t;
#define XFS_AG_MAXLEVELS(mp) ((mp)->m_ag_maxlevels)
#define XFS_MIN_FREELIST_RAW(bl,cl,mp) \
(MIN(bl + 1, XFS_AG_MAXLEVELS(mp)) + MIN(cl + 1, XFS_AG_MAXLEVELS(mp)))
#define XFS_MIN_FREELIST(a,mp) \
(XFS_MIN_FREELIST_RAW( \
be32_to_cpu((a)->agf_levels[XFS_BTNUM_BNOi]), \
be32_to_cpu((a)->agf_levels[XFS_BTNUM_CNTi]), mp))
#define XFS_MIN_FREELIST_PAG(pag,mp) \
(XFS_MIN_FREELIST_RAW( \
(uint_t)(pag)->pagf_levels[XFS_BTNUM_BNOi], \
(uint_t)(pag)->pagf_levels[XFS_BTNUM_CNTi], mp))
#define XFS_AGB_TO_FSB(mp,agno,agbno) \
(((xfs_fsblock_t)(agno) << (mp)->m_sb.sb_agblklog) | (agbno))
#define XFS_FSB_TO_AGNO(mp,fsbno) \
((xfs_agnumber_t)((fsbno) >> (mp)->m_sb.sb_agblklog))
#define XFS_FSB_TO_AGBNO(mp,fsbno) \
((xfs_agblock_t)((fsbno) & XFS_MASK32LO((mp)->m_sb.sb_agblklog)))
#define XFS_AGB_TO_DADDR(mp,agno,agbno) \
((xfs_daddr_t)XFS_FSB_TO_BB(mp, \
(xfs_fsblock_t)(agno) * (mp)->m_sb.sb_agblocks + (agbno)))
#define XFS_AG_DADDR(mp,agno,d) (XFS_AGB_TO_DADDR(mp, agno, 0) + (d))
/*
* For checking for bad ranges of xfs_daddr_t's, covering multiple
* allocation groups or a single xfs_daddr_t that's a superblock copy.
*/
#define XFS_AG_CHECK_DADDR(mp,d,len) \
((len) == 1 ? \
ASSERT((d) == XFS_SB_DADDR || \
XFS_DADDR_TO_AGBNO(mp, d) != XFS_SB_DADDR) : \
ASSERT(XFS_DADDR_TO_AGNO(mp, d) == \
XFS_DADDR_TO_AGNO(mp, (d) + (len) - 1)))
#endif /* __XFS_AG_H__ */
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