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authorChristoph Hellwig <hch@infradead.org>2011-12-18 20:00:09 +0000
committerBen Myers <bpm@sgi.com>2012-01-17 15:06:45 -0600
commit474fce067521a40dbacc722e8ba119e81c2d31bf (patch)
treefd923aa42a5304182e8a8c64ca5d130f9afef286 /fs/xfs/xfs_iget.c
parent49e4c70e52a2bc2090e5a4e003e2888af21d6a2b (diff)
xfs: replace i_flock with a sleeping bitlock
We almost never block on i_flock, the exception is synchronous inode flushing. Instead of bloating the inode with a 16/24-byte completion that we abuse as a semaphore just implement it as a bitlock that uses a bit waitqueue for the rare sleeping path. This primarily is a tradeoff between a much smaller inode and a faster non-blocking path vs faster wakeups, and we are much better off with the former. A small downside is that we will lose lockdep checking for i_flock, but given that it's always taken inside the ilock that should be acceptable. Note that for example the inode writeback locking is implemented in a very similar way. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Alex Elder <aelder@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_iget.c')
-rw-r--r--fs/xfs/xfs_iget.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index f180ce896cd7..a7cf7139f9ad 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -77,7 +77,7 @@ xfs_inode_alloc(
ASSERT(atomic_read(&ip->i_pincount) == 0);
ASSERT(!spin_is_locked(&ip->i_flags_lock));
- ASSERT(completion_done(&ip->i_flush));
+ ASSERT(!xfs_isiflocked(ip));
ASSERT(ip->i_ino == 0);
mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
@@ -150,7 +150,7 @@ xfs_inode_free(
/* asserts to verify all state is correct here */
ASSERT(atomic_read(&ip->i_pincount) == 0);
ASSERT(!spin_is_locked(&ip->i_flags_lock));
- ASSERT(completion_done(&ip->i_flush));
+ ASSERT(!xfs_isiflocked(ip));
/*
* Because we use RCU freeing we need to ensure the inode always
@@ -713,3 +713,19 @@ xfs_isilocked(
return 0;
}
#endif
+
+void
+__xfs_iflock(
+ struct xfs_inode *ip)
+{
+ wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IFLOCK_BIT);
+ DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IFLOCK_BIT);
+
+ do {
+ prepare_to_wait_exclusive(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
+ if (xfs_isiflocked(ip))
+ io_schedule();
+ } while (!xfs_iflock_nowait(ip));
+
+ finish_wait(wq, &wait.wait);
+}