The patch titled
fs/inode.c: optimize expensive assertion in end_writeback()
has been added to the -mm tree. Its filename is
fs-inodec-optimize-expensive-assertion-in-end_writeback.patch
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------------------------------------------------------
Subject: fs/inode.c: optimize expensive assertion in end_writeback()
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Taking spin_lock_irq() just to run BUG_ON() is a pretty sad use of CPU
cycles. Speed this up by only taking the lock if it looks like the
BUG_ON() will be triggering.
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/inode.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff -puN fs/inode.c~fs-inodec-optimize-expensive-assertion-in-end_writeback fs/inode.c
--- a/fs/inode.c~fs-inodec-optimize-expensive-assertion-in-end_writeback
+++ a/fs/inode.c
@@ -422,14 +422,18 @@ EXPORT_SYMBOL(remove_inode_hash);
void end_writeback(struct inode *inode)
{
might_sleep();
- /*
- * We have to cycle tree_lock here because reclaim can be still in the
- * process of removing the last page (in __delete_from_page_cache())
- * and we must not free mapping under it.
- */
- spin_lock_irq(&inode->i_data.tree_lock);
- BUG_ON(inode->i_data.nrpages);
- spin_unlock_irq(&inode->i_data.tree_lock);
+
+ if (unlikely(inode->i_data.nrpages)) {
+ /*
+ * We have to cycle tree_lock here because reclaim can be still
+ * in the process of removing the last page (in
+ * __delete_from_page_cache()) and we must not free mapping
+ * under it.
+ */
+ spin_lock_irq(&inode->i_data.tree_lock);
+ BUG_ON(inode->i_data.nrpages);
+ spin_unlock_irq(&inode->i_data.tree_lock);
+ }
BUG_ON(!list_empty(&inode->i_data.private_list));
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(inode->i_state & I_CLEAR);
_
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pci-enumerate-the-pci-device-only-removed-out-pci-hierarchy-of-os-when-re-scanning-pci-fix.patch
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drivers-staging-gma500-psb_intel_displayc-fix-build.patch
drivers-staging-dt3155v4l-dt3155v4lc-needs-slabh.patch
drivers-staging-solo6x10-corec-needs-slabh.patch
drivers-staging-solo6x10-p2mc-needs-slabh.patch
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pagewalk-add-locking-rule-comments-fix.patch
mm-memoryc-remove-zap_block_size.patch
fs-inodec-optimize-expensive-assertion-in-end_writeback.patch
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