From 3ed47db34f480df7caf44436e3e63e555351ae9a Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 22 Jan 2016 18:08:52 -0500
Subject: [PATCH] make sure that freeing shmem fast symlinks is RCU-delayed
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
include/linux/shmem_fs.h | 5 +----
mm/shmem.c | 9 ++++-----
2 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index a43f41cb3c430..4d4780c00d345 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -15,10 +15,7 @@ struct shmem_inode_info {
unsigned int seals; /* shmem seals */
unsigned long flags;
unsigned long alloced; /* data pages alloced to file */
- union {
- unsigned long swapped; /* subtotal assigned to swap */
- char *symlink; /* unswappable short symlink */
- };
+ unsigned long swapped; /* subtotal assigned to swap */
struct shared_policy policy; /* NUMA memory alloc policy */
struct list_head swaplist; /* chain of maybes on swap */
struct simple_xattrs xattrs; /* list of xattrs */
diff --git a/mm/shmem.c b/mm/shmem.c
index 38c5e72c7008c..440e2a7e6c1c2 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -701,8 +701,7 @@ static void shmem_evict_inode(struct inode *inode)
list_del_init(&info->swaplist);
mutex_unlock(&shmem_swaplist_mutex);
}
- } else
- kfree(info->symlink);
+ }
simple_xattrs_free(&info->xattrs);
WARN_ON(inode->i_blocks);
@@ -2549,13 +2548,12 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
info = SHMEM_I(inode);
inode->i_size = len-1;
if (len <= SHORT_SYMLINK_LEN) {
- info->symlink = kmemdup(symname, len, GFP_KERNEL);
- if (!info->symlink) {
+ inode->i_link = kmemdup(symname, len, GFP_KERNEL);
+ if (!inode->i_link) {
iput(inode);
return -ENOMEM;
}
inode->i_op = &shmem_short_symlink_operations;
- inode->i_link = info->symlink;
} else {
inode_nohighmem(inode);
error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
@@ -3132,6 +3130,7 @@ 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);
kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
}
--
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