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-rw-r--r--Documentation/filesystems/porting8
-rw-r--r--fs/dcache.c34
-rw-r--r--fs/inode.c1
-rw-r--r--include/linux/fs.h1
-rw-r--r--mm/shmem.c3
5 files changed, 44 insertions, 3 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 57bb3754a027..8810e2367fe6 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -531,3 +531,11 @@ in your dentry operations instead.
dentry might be yet to be attached to inode, so do _not_ use its ->d_inode
in the instances. Rationale: !@#!@# security_d_instantiate() needs to be
called before we attach dentry to inode.
+--
+[mandatory]
+ symlinks are no longer the only inodes that do *not* have i_bdev/i_cdev/
+ i_pipe/i_link union zeroed out at inode eviction. As the result, you can't
+ assume that non-NULL value in ->i_nlink at ->destroy_inode() implies that
+ it's a symlink. Checking ->i_mode is really needed now. In-tree we had
+ to fix shmem_destroy_callback() that used to take that kind of shortcut;
+ watch out, since that shortcut is no longer valid.
diff --git a/fs/dcache.c b/fs/dcache.c
index 0f1d93866e69..10988f7e5a23 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2364,6 +2364,22 @@ void d_rehash(struct dentry * entry)
}
EXPORT_SYMBOL(d_rehash);
+static inline unsigned start_dir_add(struct inode *dir)
+{
+
+ for (;;) {
+ unsigned n = dir->i_dir_seq;
+ if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
+ return n;
+ cpu_relax();
+ }
+}
+
+static inline void end_dir_add(struct inode *dir, unsigned n)
+{
+ smp_store_release(&dir->i_dir_seq, n + 2);
+}
+
void __d_lookup_done(struct dentry *dentry)
{
dentry->d_flags &= ~DCACHE_PAR_LOOKUP;
@@ -2375,9 +2391,14 @@ EXPORT_SYMBOL(__d_lookup_done);
static inline void __d_add(struct dentry *dentry, struct inode *inode)
{
+ struct inode *dir = NULL;
+ unsigned n;
spin_lock(&dentry->d_lock);
- if (unlikely(d_in_lookup(dentry)))
+ if (unlikely(d_in_lookup(dentry))) {
+ dir = dentry->d_parent->d_inode;
+ n = start_dir_add(dir);
__d_lookup_done(dentry);
+ }
if (inode) {
unsigned add_flags = d_flags_for_inode(inode);
hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
@@ -2387,6 +2408,8 @@ static inline void __d_add(struct dentry *dentry, struct inode *inode)
__fsnotify_d_instantiate(dentry);
}
_d_rehash(dentry);
+ if (dir)
+ end_dir_add(dir, n);
spin_unlock(&dentry->d_lock);
if (inode)
spin_unlock(&inode->i_lock);
@@ -2616,6 +2639,8 @@ static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
static void __d_move(struct dentry *dentry, struct dentry *target,
bool exchange)
{
+ struct inode *dir = NULL;
+ unsigned n;
if (!dentry->d_inode)
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
@@ -2623,8 +2648,11 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
BUG_ON(d_ancestor(target, dentry));
dentry_lock_for_move(dentry, target);
- if (unlikely(d_in_lookup(target)))
+ if (unlikely(d_in_lookup(target))) {
+ dir = target->d_parent->d_inode;
+ n = start_dir_add(dir);
__d_lookup_done(target);
+ }
write_seqcount_begin(&dentry->d_seq);
write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
@@ -2674,6 +2702,8 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
write_seqcount_end(&target->d_seq);
write_seqcount_end(&dentry->d_seq);
+ if (dir)
+ end_dir_add(dir, n);
dentry_unlock_for_move(dentry, target);
}
diff --git a/fs/inode.c b/fs/inode.c
index 4202aac99464..4b884f73214e 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -151,6 +151,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
inode->i_bdev = NULL;
inode->i_cdev = NULL;
inode->i_link = NULL;
+ inode->i_dir_seq = 0;
inode->i_rdev = 0;
inode->dirtied_when = 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6d0fa9174a24..00cecc5a2f75 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -684,6 +684,7 @@ struct inode {
struct block_device *i_bdev;
struct cdev *i_cdev;
char *i_link;
+ unsigned i_dir_seq;
};
__u32 i_generation;
diff --git a/mm/shmem.c b/mm/shmem.c
index 4640699b209b..e684a9140228 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3123,7 +3123,8 @@ static struct inode *shmem_alloc_inode(struct super_block *sb)
static void shmem_destroy_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
- kfree(inode->i_link);
+ if (S_ISLNK(inode->i_mode))
+ kfree(inode->i_link);
kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
}