From 949854d02455080d20cd3e1db28a3a18daf7599d Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 7 Jan 2011 17:49:37 +1100 Subject: fs: Use rename lock and RCU for multi-step operations The remaining usages for dcache_lock is to allow atomic, multi-step read-side operations over the directory tree by excluding modifications to the tree. Also, to walk in the leaf->root direction in the tree where we don't have a natural d_lock ordering. This could be accomplished by taking every d_lock, but this would mean a huge number of locks and actually gets very tricky. Solve this instead by using the rename seqlock for multi-step read-side operations, retry in case of a rename so we don't walk up the wrong parent. Concurrent dentry insertions are not serialised against. Concurrent deletes are tricky when walking up the directory: our parent might have been deleted when dropping locks so also need to check and retry for that. We can also use the rename lock in cases where livelock is a worry (and it is introduced in subsequent patch). Signed-off-by: Nick Piggin --- include/linux/dcache.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/dcache.h b/include/linux/dcache.h index bda5ec0b077d..c963ebada922 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -180,6 +180,7 @@ struct dentry_operations { #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080 /* Parent inode is watched by some fsnotify listener */ #define DCACHE_CANT_MOUNT 0x0100 +#define DCACHE_GENOCIDE 0x0200 extern spinlock_t dcache_inode_lock; extern spinlock_t dcache_lock; -- cgit v1.2.3