Cover d_name with d_lock in more cases, where there may be concurrent
modification to it.
Signed-off-by: Nick Piggin <[email protected]>
---
fs/dcache.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c 2010-11-17 00:52:37.000000000 +1100
+++ linux-2.6/fs/dcache.c 2010-11-17 01:05:42.000000000 +1100
@@ -1361,16 +1361,20 @@ static struct dentry *__d_instantiate_un
list_for_each_entry(alias, &inode->i_dentry, d_alias) {
struct qstr *qstr = &alias->d_name;
+ spin_lock(&alias->d_lock);
if (qstr->hash != hash)
- continue;
+ goto next;
if (alias->d_parent != entry->d_parent)
- continue;
+ goto next;
if (qstr->len != len)
- continue;
+ goto next;
if (memcmp(qstr->name, name, len))
- continue;
- dget_locked(alias);
+ goto next;
+ dget_locked_dlock(alias);
+ spin_unlock(&alias->d_lock);
return alias;
+next:
+ spin_unlock(&alias->d_lock);
}
__d_instantiate(entry, inode);
@@ -2298,7 +2302,9 @@ static int prepend_path(const struct pat
}
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)
@@ -2506,10 +2512,13 @@ static char *__dentry_path(struct dentry
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;