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authorAl Viro <viro@zeniv.linux.org.uk>2016-06-10 18:32:47 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2016-06-10 18:32:47 +0300
commitba65dc5ef16f82fba77869cecf7a7d515f61446b (patch)
tree58368a848f6b396be2ffcc2a43a4bee44fb354ef /include/linux/dcache.h
parent1607f09c226d1378439c411baaaa020042750338 (diff)
downloadlinux-ba65dc5ef16f82fba77869cecf7a7d515f61446b.tar.xz
much milder d_walk() race
d_walk() relies upon the tree not getting rearranged under it without rename_lock being touched. And we do grab rename_lock around the places that change the tree topology. Unfortunately, branch reordering is just as bad from d_walk() POV and we have two places that do it without touching rename_lock - one in handling of cursors (for ramfs-style directories) and another in autofs. autofs one is a separate story; this commit deals with the cursors. * mark cursor dentries explicitly at allocation time * make __dentry_kill() leave ->d_child.next pointing to the next non-cursor sibling, making sure that it won't be moved around unnoticed before the parent is relocked on ascend-to-parent path in d_walk(). * make d_walk() skip cursors explicitly; strictly speaking it's not necessary (all callbacks we pass to d_walk() are no-ops on cursors), but it makes analysis easier. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/dcache.h')
-rw-r--r--include/linux/dcache.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 484c8792da82..bcd0c64e3ed8 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -212,6 +212,7 @@ struct dentry_operations {
#define DCACHE_OP_REAL 0x08000000
#define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
+#define DCACHE_DENTRY_CURSOR 0x20000000
extern seqlock_t rename_lock;