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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 /fs/internal.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 'fs/internal.h')
-rw-r--r--fs/internal.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/internal.h b/fs/internal.h
index b71deeecea17..f57ced528cde 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -130,6 +130,7 @@ extern int invalidate_inodes(struct super_block *, bool);
extern struct dentry *__d_alloc(struct super_block *, const struct qstr *);
extern int d_set_mounted(struct dentry *dentry);
extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
+extern struct dentry *d_alloc_cursor(struct dentry *);
/*
* read_write.c