diff options
| -rw-r--r-- | fs/configfs/configfs_internal.h | 1 | ||||
| -rw-r--r-- | fs/configfs/dir.c | 53 |
2 files changed, 44 insertions, 10 deletions
diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h index 5a33b58..da015c1 100644 --- a/fs/configfs/configfs_internal.h +++ b/fs/configfs/configfs_internal.h @@ -48,6 +48,7 @@ struct configfs_dirent { #define CONFIGFS_USET_DIR 0x0040 #define CONFIGFS_USET_DEFAULT 0x0080 #define CONFIGFS_USET_DROPPING 0x0100 +#define CONFIGFS_USET_IN_MKDIR 0x0200 #define CONFIGFS_NOT_PINNED (CONFIGFS_ITEM_ATTR) extern spinlock_t configfs_dirent_lock; diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index d5b5985..614e382 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -364,7 +364,7 @@ static struct dentry * configfs_lookup(struct inode *dir, * If there is an error, the caller will reset the flags via * configfs_detach_rollback(). */ -static int configfs_detach_prep(struct dentry *dentry) +static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex) { struct configfs_dirent *parent_sd = dentry->d_fsdata; struct configfs_dirent *sd; @@ -379,6 +379,12 @@ static int configfs_detach_prep(struct dentry *dentry) if (sd->s_type & CONFIGFS_NOT_PINNED) continue; if (sd->s_type & CONFIGFS_USET_DEFAULT) { + /* Abort if racing with mkdir() */ + if (sd->s_type & CONFIGFS_USET_IN_MKDIR) { + if (wait_mutex) + *wait_mutex = &sd->s_dentry->d_inode->i_mutex; + return -EAGAIN; + } /* Mark that we're trying to drop the group */ sd->s_type |= CONFIGFS_USET_DROPPING; @@ -386,7 +392,7 @@ static int configfs_detach_prep(struct dentry *dentry) * Yup, recursive. If there's a problem, blame * deep nesting of default_groups */ - ret = configfs_detach_prep(sd->s_dentry); + ret = configfs_detach_prep(sd->s_dentry, wait_mutex); if (!ret) continue; } else @@ -1113,11 +1119,26 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) */ module_got = 1; + /* + * Make racing rmdir() fail if it did not tag parent with + * CONFIGFS_USET_DROPPING + * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will + * fail and let rmdir() terminate correctly + */ + spin_lock(&configfs_dirent_lock); + /* This will make configfs_detach_prep() fail */ + sd->s_type |= CONFIGFS_USET_IN_MKDIR; + spin_unlock(&configfs_dirent_lock); + if (group) ret = configfs_attach_group(parent_item, item, dentry); else ret = configfs_attach_item(parent_item, item, dentry); + spin_lock(&configfs_dirent_lock); + sd->s_type &= ~CONFIGFS_USET_IN_MKDIR; + spin_unlock(&configfs_dirent_lock); + out_unlink: if (ret) { /* Tear down everything we built up */ @@ -1182,13 +1203,25 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry) } spin_lock(&configfs_dirent_lock); - ret = configfs_detach_prep(dentry); - if (ret) { - configfs_detach_rollback(dentry); - spin_unlock(&configfs_dirent_lock); - config_item_put(parent_item); - return ret; - } + do { + struct mutex *wait_mutex; + + ret = configfs_detach_prep(dentry, &wait_mutex); + if (ret) { + configfs_detach_rollback(dentry); + spin_unlock(&configfs_dirent_lock); + if (ret != -EAGAIN) { + config_item_put(parent_item); + return ret; + } + + /* Wait until the racing operation terminates */ + mutex_lock(wait_mutex); + mutex_unlock(wait_mutex); + + spin_lock(&configfs_dirent_lock); + } + } while (ret == -EAGAIN); spin_unlock(&configfs_dirent_lock); /* Get a working ref for the duration of this function */ @@ -1480,7 +1513,7 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys) I_MUTEX_PARENT); mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD); spin_lock(&configfs_dirent_lock); - if (configfs_detach_prep(dentry)) { + if (configfs_detach_prep(dentry, NULL)) { printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n"); } spin_unlock(&configfs_dirent_lock); |
