From 4196ac08c023c6dab90c3fa460d9c06deaa304c4 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 11 Jan 2010 11:47:42 +0000 Subject: xfs: Convert filestreams code to use per-ag get/put routines Use xfs_perag_get() and xfs_perag_put() in the filestreams code. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/xfs_filestream.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) (limited to 'fs/xfs/xfs_filestream.c') diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c index a631e1451abb..e61f2aa088a9 100644 --- a/fs/xfs/xfs_filestream.c +++ b/fs/xfs/xfs_filestream.c @@ -140,6 +140,7 @@ _xfs_filestream_pick_ag( int flags, xfs_extlen_t minlen) { + int streams, max_streams; int err, trylock, nscan; xfs_extlen_t longest, free, minfree, maxfree = 0; xfs_agnumber_t ag, max_ag = NULLAGNUMBER; @@ -155,15 +156,15 @@ _xfs_filestream_pick_ag( trylock = XFS_ALLOC_FLAG_TRYLOCK; for (nscan = 0; 1; nscan++) { - - TRACE_AG_SCAN(mp, ag, xfs_filestream_peek_ag(mp, ag)); - - pag = mp->m_perag + ag; + pag = xfs_perag_get(mp, ag); + TRACE_AG_SCAN(mp, ag, atomic_read(&pag->pagf_fstrms)); if (!pag->pagf_init) { err = xfs_alloc_pagf_init(mp, NULL, ag, trylock); - if (err && !trylock) + if (err && !trylock) { + xfs_perag_put(pag); return err; + } } /* Might fail sometimes during the 1st pass with trylock set. */ @@ -173,6 +174,7 @@ _xfs_filestream_pick_ag( /* Keep track of the AG with the most free blocks. */ if (pag->pagf_freeblks > maxfree) { maxfree = pag->pagf_freeblks; + max_streams = atomic_read(&pag->pagf_fstrms); max_ag = ag; } @@ -195,6 +197,8 @@ _xfs_filestream_pick_ag( /* Break out, retaining the reference on the AG. */ free = pag->pagf_freeblks; + streams = atomic_read(&pag->pagf_fstrms); + xfs_perag_put(pag); *agp = ag; break; } @@ -202,6 +206,7 @@ _xfs_filestream_pick_ag( /* Drop the reference on this AG, it's not usable. */ xfs_filestream_put_ag(mp, ag); next_ag: + xfs_perag_put(pag); /* Move to the next AG, wrapping to AG 0 if necessary. */ if (++ag >= mp->m_sb.sb_agcount) ag = 0; @@ -229,6 +234,7 @@ next_ag: if (max_ag != NULLAGNUMBER) { xfs_filestream_get_ag(mp, max_ag); TRACE_AG_PICK1(mp, max_ag, maxfree); + streams = max_streams; free = maxfree; *agp = max_ag; break; @@ -240,8 +246,7 @@ next_ag: return 0; } - TRACE_AG_PICK2(mp, startag, *agp, xfs_filestream_peek_ag(mp, *agp), - free, nscan, flags); + TRACE_AG_PICK2(mp, startag, *agp, streams, free, nscan, flags); return 0; } -- cgit v1.2.3 From 1c1c6ebcf5284aee4910f3b906ac90c20e510c82 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 11 Jan 2010 11:47:44 +0000 Subject: xfs: Replace per-ag array with a radix tree The use of an array for the per-ag structures requires reallocation of the array when growing the filesystem. This requires locking access to the array to avoid use after free situations, and the locking is difficult to get right. To avoid needing to reallocate an array, change the per-ag structures to an allocated object per ag and index them using a tree structure. The AGs are always densely indexed (hence the use of an array), but the number supported is 2^32 and lookups tend to be random and hence indexing needs to scale. A simple choice is a radix tree - it works well with this sort of index. This change also removes another large contiguous allocation from the mount/growfs path in XFS. The growing process now needs to change to only initialise the new AGs required for the extra space, and as such only needs to exclusively lock the tree for inserts. The rest of the code only needs to lock the tree while doing lookups, and hence this will remove all the deadlocks that currently occur on the m_perag_lock as it is now an innermost lock. The lock is also changed to a spinlock from a read/write lock as the hold time is now extremely short. To complete the picture, the per-ag structures will need to be reference counted to ensure that we don't free/modify them while they are still in use. This will be done in subsequent patch. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/xfs_filestream.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) (limited to 'fs/xfs/xfs_filestream.c') diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c index e61f2aa088a9..914d00d0f119 100644 --- a/fs/xfs/xfs_filestream.c +++ b/fs/xfs/xfs_filestream.c @@ -253,8 +253,7 @@ next_ag: /* * Set the allocation group number for a file or a directory, updating inode - * references and per-AG references as appropriate. Must be called with the - * m_peraglock held in read mode. + * references and per-AG references as appropriate. */ static int _xfs_filestream_update_ag( @@ -456,10 +455,10 @@ xfs_filestream_unmount( } /* - * If the mount point's m_perag array is going to be reallocated, all + * If the mount point's m_perag tree is going to be modified, all * outstanding cache entries must be flushed to avoid accessing reference count * addresses that have been freed. The call to xfs_filestream_flush() must be - * made inside the block that holds the m_peraglock in write mode to do the + * made inside the block that holds the m_perag_lock in write mode to do the * reallocation. */ void @@ -531,7 +530,6 @@ xfs_filestream_associate( mp = pip->i_mount; cache = mp->m_filestream; - down_read(&mp->m_peraglock); /* * We have a problem, Houston. @@ -548,10 +546,8 @@ xfs_filestream_associate( * * So, if we can't get the iolock without sleeping then just give up */ - if (!xfs_ilock_nowait(pip, XFS_IOLOCK_EXCL)) { - up_read(&mp->m_peraglock); + if (!xfs_ilock_nowait(pip, XFS_IOLOCK_EXCL)) return 1; - } /* If the parent directory is already in the cache, use its AG. */ item = xfs_mru_cache_lookup(cache, pip->i_ino); @@ -606,7 +602,6 @@ exit_did_pick: exit: xfs_iunlock(pip, XFS_IOLOCK_EXCL); - up_read(&mp->m_peraglock); return -err; } -- cgit v1.2.3 From b657fc82a3ca6d7ad16a59e81765f0fb0e86cdbb Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 11 Jan 2010 11:47:47 +0000 Subject: xfs: Kill filestreams cache flush The filestreams cache flush is not needed in the sync code as it does not affect data writeback, and it is now not used by the growfs code, either, so kill it. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/xfs_filestream.c | 14 -------------- 1 file changed, 14 deletions(-) (limited to 'fs/xfs/xfs_filestream.c') diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c index 914d00d0f119..390850ee6603 100644 --- a/fs/xfs/xfs_filestream.c +++ b/fs/xfs/xfs_filestream.c @@ -454,20 +454,6 @@ xfs_filestream_unmount( xfs_mru_cache_destroy(mp->m_filestream); } -/* - * If the mount point's m_perag tree is going to be modified, all - * outstanding cache entries must be flushed to avoid accessing reference count - * addresses that have been freed. The call to xfs_filestream_flush() must be - * made inside the block that holds the m_perag_lock in write mode to do the - * reallocation. - */ -void -xfs_filestream_flush( - xfs_mount_t *mp) -{ - xfs_mru_cache_flush(mp->m_filestream); -} - /* * Return the AG of the filestream the file or directory belongs to, or * NULLAGNUMBER otherwise. -- cgit v1.2.3