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fs/9p: Fix race in initializing writeback fid

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When two process open the same file we can end up with both of them
allocating the writeback_fid. Add a new mutex which can be used
for synchronizing v9fs_inode member values.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
This commit is contained in:
Aneesh Kumar K.V 2011-03-08 16:39:46 +05:30 committed by Eric Van Hensbergen
parent f741a79e98
commit 5a7e0a8cf5
4 changed files with 11 additions and 0 deletions
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1
fs/9p/v9fs.h
View File

@ -130,6 +130,7 @@ struct v9fs_inode {
#endif
unsigned int cache_validity;
struct p9_fid *writeback_fid;
struct mutex v_mutex;
struct inode vfs_inode;
};

3
fs/9p/vfs_file.c
View File

@ -90,6 +90,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
}
file->private_data = fid;
mutex_lock(&v9inode->v_mutex);
if (v9ses->cache && !v9inode->writeback_fid) {
/*
* clone a fid and add it to writeback_fid
@ -101,10 +102,12 @@ int v9fs_file_open(struct inode *inode, struct file *file)
fid = v9fs_writeback_fid(file->f_path.dentry);
if (IS_ERR(fid)) {
err = PTR_ERR(fid);
mutex_unlock(&v9inode->v_mutex);
goto out_error;
}
v9inode->writeback_fid = (void *) fid;
}
mutex_unlock(&v9inode->v_mutex);
#ifdef CONFIG_9P_FSCACHE
if (v9ses->cache)
v9fs_cache_inode_set_cookie(inode, file);

4
fs/9p/vfs_inode.c
View File

@ -221,6 +221,7 @@ struct inode *v9fs_alloc_inode(struct super_block *sb)
#endif
v9inode->writeback_fid = NULL;
v9inode->cache_validity = 0;
mutex_init(&v9inode->v_mutex);
return &v9inode->vfs_inode;
}
@ -650,6 +651,7 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, int mode,
/* if we are opening a file, assign the open fid to the file */
if (nd && nd->flags & LOOKUP_OPEN) {
v9inode = V9FS_I(dentry->d_inode);
mutex_lock(&v9inode->v_mutex);
if (v9ses->cache && !v9inode->writeback_fid) {
/*
* clone a fid and add it to writeback_fid
@ -661,10 +663,12 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, int mode,
inode_fid = v9fs_writeback_fid(dentry);
if (IS_ERR(inode_fid)) {
err = PTR_ERR(inode_fid);
mutex_unlock(&v9inode->v_mutex);
goto error;
}
v9inode->writeback_fid = (void *) inode_fid;
}
mutex_unlock(&v9inode->v_mutex);
filp = lookup_instantiate_filp(nd, dentry, generic_file_open);
if (IS_ERR(filp)) {
err = PTR_ERR(filp);

3
fs/9p/vfs_inode_dotl.c
View File

@ -245,6 +245,7 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, int omode,
v9fs_set_create_acl(dentry, dacl, pacl);
v9inode = V9FS_I(inode);
mutex_lock(&v9inode->v_mutex);
if (v9ses->cache && !v9inode->writeback_fid) {
/*
* clone a fid and add it to writeback_fid
@ -256,10 +257,12 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, int omode,
inode_fid = v9fs_writeback_fid(dentry);
if (IS_ERR(inode_fid)) {
err = PTR_ERR(inode_fid);
mutex_unlock(&v9inode->v_mutex);
goto error;
}
v9inode->writeback_fid = (void *) inode_fid;
}
mutex_unlock(&v9inode->v_mutex);
/* Since we are opening a file, assign the open fid to the file */
filp = lookup_instantiate_filp(nd, dentry, generic_file_open);
if (IS_ERR(filp)) {