From 9abca36087288fe28de4749c71ca003d4b9e3ed0 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 7 Jan 2011 17:49:36 +1100 Subject: [PATCH] fs: increase d_name lock coverage Cover d_name with d_lock in more cases, where there may be concurrent modification to it. Signed-off-by: Nick Piggin --- fs/dcache.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index de38680ee0e..a09f0771fd2 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1350,6 +1350,11 @@ static struct dentry *__d_instantiate_unique(struct dentry *entry, list_for_each_entry(alias, &inode->i_dentry, d_alias) { struct qstr *qstr = &alias->d_name; + /* + * Don't need alias->d_lock here, because aliases with + * d_parent == entry->d_parent are not subject to name or + * parent changes, because the parent inode i_mutex is held. + */ if (qstr->hash != hash) continue; if (alias->d_parent != entry->d_parent) @@ -2313,7 +2318,9 @@ static int prepend_path(const struct path *path, struct path *root, } parent = dentry->d_parent; prefetch(parent); + spin_lock(&dentry->d_lock); error = prepend_name(buffer, buflen, &dentry->d_name); + spin_unlock(&dentry->d_lock); if (!error) error = prepend(buffer, buflen, "/", 1); if (error) @@ -2515,10 +2522,13 @@ static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) while (!IS_ROOT(dentry)) { struct dentry *parent = dentry->d_parent; + int error; prefetch(parent); - if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || - (prepend(&end, &buflen, "/", 1) != 0)) + spin_lock(&dentry->d_lock); + error = prepend_name(&end, &buflen, &dentry->d_name); + spin_unlock(&dentry->d_lock); + if (error != 0 || prepend(&end, &buflen, "/", 1) != 0) goto Elong; retval = end; -- 2.20.1