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-rw-r--r--Documentation/filesystems/Locking2
-rw-r--r--Documentation/filesystems/porting25
-rw-r--r--fs/inode.c56
-rw-r--r--include/linux/fs.h6
4 files changed, 66 insertions, 23 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index efea228ccd8a..7b20c385cc02 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -118,6 +118,7 @@ set: exclusive
--------------------------- super_operations ---------------------------
prototypes:
struct inode *(*alloc_inode)(struct super_block *sb);
+ void (*free_inode)(struct inode *);
void (*destroy_inode)(struct inode *);
void (*dirty_inode) (struct inode *, int flags);
int (*write_inode) (struct inode *, struct writeback_control *wbc);
@@ -139,6 +140,7 @@ locking rules:
All may block [not true, see below]
s_umount
alloc_inode:
+free_inode: called from RCU callback
destroy_inode:
dirty_inode:
write_inode:
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index cf43bc4dbf31..b8d3ddd8b8db 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -638,3 +638,28 @@ in your dentry operations instead.
inode to d_splice_alias() will also do the right thing (equivalent of
d_add(dentry, NULL); return NULL;), so that kind of special cases
also doesn't need a separate treatment.
+--
+[strongly recommended]
+ take the RCU-delayed parts of ->destroy_inode() into a new method -
+ ->free_inode(). If ->destroy_inode() becomes empty - all the better,
+ just get rid of it. Synchronous work (e.g. the stuff that can't
+ be done from an RCU callback, or any WARN_ON() where we want the
+ stack trace) *might* be movable to ->evict_inode(); however,
+ that goes only for the things that are not needed to balance something
+ done by ->alloc_inode(). IOW, if it's cleaning up the stuff that
+ might have accumulated over the life of in-core inode, ->evict_inode()
+ might be a fit.
+
+ Rules for inode destruction:
+ * if ->destroy_inode() is non-NULL, it gets called
+ * if ->free_inode() is non-NULL, it gets scheduled by call_rcu()
+ * combination of NULL ->destroy_inode and NULL ->free_inode is
+ treated as NULL/free_inode_nonrcu, to preserve the compatibility.
+
+ Note that the callback (be it via ->free_inode() or explicit call_rcu()
+ in ->destroy_inode()) is *NOT* ordered wrt superblock destruction;
+ as the matter of fact, the superblock and all associated structures
+ might be already gone. The filesystem driver is guaranteed to be still
+ there, but that's it. Freeing memory in the callback is fine; doing
+ more than that is possible, but requires a lot of care and is best
+ avoided.
diff --git a/fs/inode.c b/fs/inode.c
index e9d97add2b36..627e1766503a 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -202,12 +202,28 @@ out:
}
EXPORT_SYMBOL(inode_init_always);
+void free_inode_nonrcu(struct inode *inode)
+{
+ kmem_cache_free(inode_cachep, inode);
+}
+EXPORT_SYMBOL(free_inode_nonrcu);
+
+static void i_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+ if (inode->free_inode)
+ inode->free_inode(inode);
+ else
+ free_inode_nonrcu(inode);
+}
+
static struct inode *alloc_inode(struct super_block *sb)
{
+ const struct super_operations *ops = sb->s_op;
struct inode *inode;
- if (sb->s_op->alloc_inode)
- inode = sb->s_op->alloc_inode(sb);
+ if (ops->alloc_inode)
+ inode = ops->alloc_inode(sb);
else
inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
@@ -215,22 +231,19 @@ static struct inode *alloc_inode(struct super_block *sb)
return NULL;
if (unlikely(inode_init_always(sb, inode))) {
- if (inode->i_sb->s_op->destroy_inode)
- inode->i_sb->s_op->destroy_inode(inode);
- else
- kmem_cache_free(inode_cachep, inode);
+ if (ops->destroy_inode) {
+ ops->destroy_inode(inode);
+ if (!ops->free_inode)
+ return NULL;
+ }
+ inode->free_inode = ops->free_inode;
+ i_callback(&inode->i_rcu);
return NULL;
}
return inode;
}
-void free_inode_nonrcu(struct inode *inode)
-{
- kmem_cache_free(inode_cachep, inode);
-}
-EXPORT_SYMBOL(free_inode_nonrcu);
-
void __destroy_inode(struct inode *inode)
{
BUG_ON(inode_has_buffers(inode));
@@ -253,20 +266,19 @@ void __destroy_inode(struct inode *inode)
}
EXPORT_SYMBOL(__destroy_inode);
-static void i_callback(struct rcu_head *head)
-{
- struct inode *inode = container_of(head, struct inode, i_rcu);
- kmem_cache_free(inode_cachep, inode);
-}
-
static void destroy_inode(struct inode *inode)
{
+ const struct super_operations *ops = inode->i_sb->s_op;
+
BUG_ON(!list_empty(&inode->i_lru));
__destroy_inode(inode);
- if (inode->i_sb->s_op->destroy_inode)
- inode->i_sb->s_op->destroy_inode(inode);
- else
- call_rcu(&inode->i_rcu, i_callback);
+ if (ops->destroy_inode) {
+ ops->destroy_inode(inode);
+ if (!ops->free_inode)
+ return;
+ }
+ inode->free_inode = ops->free_inode;
+ call_rcu(&inode->i_rcu, i_callback);
}
/**
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dd28e7679089..92732286b748 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -694,7 +694,10 @@ struct inode {
#ifdef CONFIG_IMA
atomic_t i_readcount; /* struct files open RO */
#endif
- const struct file_operations *i_fop; /* former ->i_op->default_file_ops */
+ union {
+ const struct file_operations *i_fop; /* former ->i_op->default_file_ops */
+ void (*free_inode)(struct inode *);
+ };
struct file_lock_context *i_flctx;
struct address_space i_data;
struct list_head i_devices;
@@ -1903,6 +1906,7 @@ extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
+ void (*free_inode)(struct inode *);
void (*dirty_inode) (struct inode *, int flags);
int (*write_inode) (struct inode *, struct writeback_control *wbc);