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| author | Al Viro <viro@zeniv.linux.org.uk> | 2016-06-10 17:32:47 +0200 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2016-06-10 17:32:47 +0200 |
| commit | ba65dc5ef16f82fba77869cecf7a7d515f61446b (patch) | |
| tree | 58368a848f6b396be2ffcc2a43a4bee44fb354ef /include | |
| parent | coredump: fix dumping through pipes (diff) | |
| download | linux-ba65dc5ef16f82fba77869cecf7a7d515f61446b.tar.xz linux-ba65dc5ef16f82fba77869cecf7a7d515f61446b.zip | |
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')
| -rw-r--r-- | include/linux/dcache.h | 1 |
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; |