From c999a223c2f0d31c64ef7379814cea1378b2b800 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 22 Mar 2012 05:15:07 +0000 Subject: xfs: introduce an allocation workqueue We currently have significant issues with the amount of stack that allocation in XFS uses, especially in the writeback path. We can easily consume 4k of stack between mapping the page, manipulating the bmap btree and allocating blocks from the free list. Not to mention btree block readahead and other functionality that issues IO in the allocation path. As a result, we can no longer fit allocation in the writeback path in the stack space provided on x86_64. To alleviate this problem, introduce an allocation workqueue and move all allocations to a seperate context. This can be easily added as an interposing layer into xfs_alloc_vextent(), which takes a single argument structure and does not return until the allocation is complete or has failed. To do this, add a work structure and a completion to the allocation args structure. This allows xfs_alloc_vextent to queue the args onto the workqueue and wait for it to be completed by the worker. This can be done completely transparently to the caller. The worker function needs to ensure that it sets and clears the PF_TRANS flag appropriately as it is being run in an active transaction context. Work can also be queued in a memory reclaim context, so a rescuer is needed for the workqueue. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers --- fs/xfs/xfs_alloc.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'fs/xfs/xfs_alloc.h') diff --git a/fs/xfs/xfs_alloc.h b/fs/xfs/xfs_alloc.h index 2f52b924be79..ab5d0fd2f535 100644 --- a/fs/xfs/xfs_alloc.h +++ b/fs/xfs/xfs_alloc.h @@ -25,6 +25,8 @@ struct xfs_perag; struct xfs_trans; struct xfs_busy_extent; +extern struct workqueue_struct *xfs_alloc_wq; + /* * Freespace allocation types. Argument to xfs_alloc_[v]extent. */ @@ -119,6 +121,9 @@ typedef struct xfs_alloc_arg { char isfl; /* set if is freelist blocks - !acctg */ char userdata; /* set if this is user data */ xfs_fsblock_t firstblock; /* io first block allocated */ + struct completion *done; + struct work_struct work; + int result; } xfs_alloc_arg_t; /* -- cgit v1.2.3 From a66d636385d621e98a915233250356c394a437de Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 22 Mar 2012 05:15:12 +0000 Subject: xfs: fix fstrim offset calculations xfs_ioc_fstrim() doesn't treat the incoming offset and length correctly. It treats them as a filesystem block address, rather than a disk address. This is wrong because the range passed in is a linear representation, while the filesystem block address notation is a sparse representation. Hence we cannot convert the range direct to filesystem block units and then use that for calculating the range to trim. While this sounds dangerous, the problem is limited to calculating what AGs need to be trimmed. The code that calcuates the actual ranges to trim gets the right result (i.e. only ever discards free space), even though it uses the wrong ranges to limit what is trimmed. Hence this is not a bug that endangers user data. Fix this by treating the range as a disk address range and use the appropriate functions to convert the range into the desired formats for calculations. Further, fix the first free extent lookup (the longest) to actually find the largest free extent. Currently this lookup uses a <= lookup, which results in finding the extent to the left of the largest because we can never get an exact match on the largest extent. This is due to the fact that while we know it's size, we don't know it's location and so the exact match fails and we move one record to the left to get the next largest extent. Instead, use a >= search so that the lookup returns the largest extent regardless of the fact we don't get an exact match on it. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers --- fs/xfs/xfs_alloc.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/xfs/xfs_alloc.h') diff --git a/fs/xfs/xfs_alloc.h b/fs/xfs/xfs_alloc.h index ab5d0fd2f535..3a7e7d8f8ded 100644 --- a/fs/xfs/xfs_alloc.h +++ b/fs/xfs/xfs_alloc.h @@ -248,6 +248,13 @@ xfs_alloc_lookup_le( xfs_extlen_t len, /* length of extent */ int *stat); /* success/failure */ +int /* error */ +xfs_alloc_lookup_ge( + struct xfs_btree_cur *cur, /* btree cursor */ + xfs_agblock_t bno, /* starting block of extent */ + xfs_extlen_t len, /* length of extent */ + int *stat); /* success/failure */ + int /* error */ xfs_alloc_get_rec( struct xfs_btree_cur *cur, /* btree cursor */ -- cgit v1.2.3