[PATCH 32/32] SUNRPC: cache must take a reference to the cache detail's module on open()

Trond Myklebust
2009-08-19T23:41:02Z

Otherwise we Oops if the module containing the cache detail is removed
before all cache readers have closed the file.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
net/sunrpc/cache.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 76 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index db7720e..45cdaff 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -836,6 +836,8 @@ static int cache_open(struct inode *inode, struct file *filp,
{
struct cache_reader *rp = NULL;

+ if (!cd || !try_module_get(cd->owner))
+ return -EACCES;
nonseekable_open(inode, filp);
if (filp->f_mode & FMODE_READ) {
rp = kmalloc(sizeof(*rp), GFP_KERNEL);
@@ -879,6 +881,7 @@ static int cache_release(struct inode *inode, struct file *filp,
cd->last_close = get_seconds();
atomic_dec(&cd->readers);
}
+ module_put(cd->owner);
return 0;
}

@@ -1215,6 +1218,8 @@ static int content_open(struct inode *inode, struct file *file,
{
struct handle *han;

+ if (!cd || !try_module_get(cd->owner))
+ return -EACCES;
han = __seq_open_private(file, &cache_content_op, sizeof(*han));
if (han == NULL)
return -ENOMEM;
@@ -1223,6 +1228,29 @@ static int content_open(struct inode *inode, struct file *file,
return 0;
}

+static int content_release(struct inode *inode, struct file *file,
+ struct cache_detail *cd)
+{
+ int ret = seq_release_private(inode, file);
+ module_put(cd->owner);
+ return ret;
+}
+
+static int open_flush(struct inode *inode, struct file *file,
+ struct cache_detail *cd)
+{
+ if (!cd || !try_module_get(cd->owner))
+ return -EACCES;
+ return nonseekable_open(inode, file);
+}
+
+static int release_flush(struct inode *inode, struct file *file,
+ struct cache_detail *cd)
+{
+ module_put(cd->owner);
+ return 0;
+}
+
static ssize_t read_flush(struct file *file, char __user *buf,
size_t count, loff_t *ppos,
struct cache_detail *cd)
@@ -1331,13 +1359,34 @@ static int content_open_procfs(struct inode *inode, struct file *filp)
return content_open(inode, filp, cd);
}

+static int content_release_procfs(struct inode *inode, struct file *filp)
+{
+ struct cache_detail *cd = PDE(inode)->data;
+
+ return content_release(inode, filp, cd);
+}
+
static const struct file_operations content_file_operations_procfs = {
.open = content_open_procfs,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release_private,
+ .release = content_release_procfs,
};

+static int open_flush_procfs(struct inode *inode, struct file *filp)
+{
+ struct cache_detail *cd = PDE(inode)->data;
+
+ return open_flush(inode, filp, cd);
+}
+
+static int release_flush_procfs(struct inode *inode, struct file *filp)
+{
+ struct cache_detail *cd = PDE(inode)->data;
+
+ return release_flush(inode, filp, cd);
+}
+
static ssize_t read_flush_procfs(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -1356,9 +1405,10 @@ static ssize_t write_flush_procfs(struct file *filp,
}

static const struct file_operations cache_flush_operations_procfs = {
- .open = nonseekable_open,
+ .open = open_flush_procfs,
.read = read_flush_procfs,
.write = write_flush_procfs,
+ .release = release_flush_procfs,
};

static void remove_cache_proc_entries(struct cache_detail *cd)
@@ -1503,13 +1553,34 @@ static int content_open_pipefs(struct inode *inode, struct file *filp)
return content_open(inode, filp, cd);
}

+static int content_release_pipefs(struct inode *inode, struct file *filp)
+{
+ struct cache_detail *cd = RPC_I(inode)->private;
+
+ return content_release(inode, filp, cd);
+}
+
const struct file_operations content_file_operations_pipefs = {
.open = content_open_pipefs,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release_private,
+ .release = content_release_pipefs,
};

+static int open_flush_pipefs(struct inode *inode, struct file *filp)
+{
+ struct cache_detail *cd = RPC_I(inode)->private;
+
+ return open_flush(inode, filp, cd);
+}
+
+static int release_flush_pipefs(struct inode *inode, struct file *filp)
+{
+ struct cache_detail *cd = RPC_I(inode)->private;
+
+ return release_flush(inode, filp, cd);
+}
+
static ssize_t read_flush_pipefs(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -1528,9 +1599,10 @@ static ssize_t write_flush_pipefs(struct file *filp,
}

const struct file_operations cache_flush_operations_pipefs = {
- .open = nonseekable_open,
+ .open = open_flush_pipefs,
.read = read_flush_pipefs,
.write = write_flush_pipefs,
+ .release = release_flush_pipefs,
};

int sunrpc_cache_register_pipefs(struct dentry *parent,
--
1.6.0.4