From: "leilei.lin" <leilei....@alibaba-inc.com>
locklessly and integrally copy dentry name. It will be used later for
bugfix
Signed-off-by: leilei.lin <leilei....@alibaba-inc.com>
---
fs/dcache.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/dcache.h | 2 ++
2 files changed, 40 insertions(+)
diff --git a/fs/dcache.c b/fs/dcache.c
index 95d71ed..056249b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3536,6 +3536,44 @@ void d_tmpfile(struct dentry *dentry, struct inode
*inode)
}
EXPORT_SYMBOL(d_tmpfile);
+int copy_dname(struct dentry *dentry, char **name)
+{
+ unsigned int seq;
+ const char *dname;
+
+ /* in case that dentry was being free */
+ rcu_read_lock();
+
+ dname = dentry->d_name.name;
+
+ if (unlikely(!dname)) {
+ rcu_read_unlock();
+ return 0;
+ }
+
+ if (unlikely(dname != dentry->d_iname)) {
+ *name = kstrdup(dname, GFP_ATOMIC);
+ rcu_read_unlock();
+ if (unlikely(!*name))
+ return -ENOMEM;
+
+ return 0;
+ }
+
+ rcu_read_unlock();
+ *name = kmalloc(DNAME_INLINE_LEN, GFP_KERNEL);
+ if (unlikely(!*name))
+ return -ENOMEM;
+
+ do {
+ seq = read_seqcount_begin(&dentry->d_seq);
+ strcpy(*name, dname);
+ } while (read_seqcount_retry(&dentry->d_seq, seq));
+
+ return 0;
+}
+EXPORT_SYMBOL(copy_dname);
+
static __initdata unsigned long dhash_entries;
static int __init set_dhash_entries(char *str)
{
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index d2e38dc..a1b2aeb 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -296,6 +296,8 @@ extern char *d_path(const struct path *, char *, int);
extern char *dentry_path_raw(struct dentry *, char *, int);
extern char *dentry_path(struct dentry *, char *, int);
+extern int copy_dname(struct dentry *dentry, char **name);
+
/* Allocation counts.. */
/**
--
2.8.4.31.g9ed660f
