diff options
| -rw-r--r-- | fs/fs-writeback.c | 5 | ||||
| -rw-r--r-- | include/linux/backing-dev.h | 34 |
2 files changed, 35 insertions, 4 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 25458fa4753d..6b99deeb9de0 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -285,7 +285,8 @@ locked_inode_to_wb_and_lock_list(struct inode *inode) spin_lock(&wb->list_lock); wb_put(wb); /* not gonna deref it anymore */ - if (likely(wb == inode_to_wb(inode))) + /* i_wb may have changed inbetween, can't use inode_to_wb() */ + if (likely(wb == inode->i_wb)) return wb; /* @inode already has ref */ spin_unlock(&wb->list_lock); @@ -622,7 +623,7 @@ int inode_congested(struct inode *inode, int cong_bits) * Once set, ->i_wb never becomes NULL while the inode is alive. * Start transaction iff ->i_wb is visible. */ - if (inode && inode_to_wb(inode)) { + if (inode && inode_to_wb_is_valid(inode)) { struct bdi_writeback *wb; bool locked, congested; diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 73ffa32e58ee..dfce80869145 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -322,13 +322,33 @@ wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp) } /** + * inode_to_wb_is_valid - test whether an inode has a wb associated + * @inode: inode of interest + * + * Returns %true if @inode has a wb associated. May be called without any + * locking. + */ +static inline bool inode_to_wb_is_valid(struct inode *inode) +{ + return inode->i_wb; +} + +/** * inode_to_wb - determine the wb of an inode * @inode: inode of interest * - * Returns the wb @inode is currently associated with. + * Returns the wb @inode is currently associated with. The caller must be + * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the + * associated wb's list_lock. */ static inline struct bdi_writeback *inode_to_wb(struct inode *inode) { +#ifdef CONFIG_LOCKDEP + WARN_ON_ONCE(debug_locks && + (!lockdep_is_held(&inode->i_lock) && + !lockdep_is_held(&inode->i_mapping->tree_lock) && + !lockdep_is_held(&inode->i_wb->list_lock))); +#endif return inode->i_wb; } @@ -360,7 +380,12 @@ unlocked_inode_to_wb_begin(struct inode *inode, bool *lockedp) if (unlikely(*lockedp)) spin_lock_irq(&inode->i_mapping->tree_lock); - return inode_to_wb(inode); + + /* + * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock. + * inode_to_wb() will bark. Deref directly. + */ + return inode->i_wb; } /** @@ -459,6 +484,11 @@ wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp) return &bdi->wb; } +static inline bool inode_to_wb_is_valid(struct inode *inode) +{ + return true; +} + static inline struct bdi_writeback *inode_to_wb(struct inode *inode) { return &inode_to_bdi(inode)->wb; |