diff options
| -rw-r--r-- | fs/fs-writeback.c | 66 | ||||
| -rw-r--r-- | fs/inode.c | 8 | ||||
| -rw-r--r-- | include/linux/fs.h | 7 | ||||
| -rw-r--r-- | include/linux/writeback.h | 7 |
4 files changed, 65 insertions, 23 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 5f2c68289610..8d2fb8c88cf3 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -326,9 +326,12 @@ static int write_inode(struct inode *inode, struct writeback_control *wbc) } /* - * Wait for writeback on an inode to complete. + * Wait for writeback on an inode to complete. Called with i_lock held. + * Caller must make sure inode cannot go away when we drop i_lock. */ -static void inode_wait_for_writeback(struct inode *inode) +static void __inode_wait_for_writeback(struct inode *inode) + __releases(inode->i_lock) + __acquires(inode->i_lock) { DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); wait_queue_head_t *wqh; @@ -342,6 +345,36 @@ static void inode_wait_for_writeback(struct inode *inode) } /* + * Wait for writeback on an inode to complete. Caller must have inode pinned. + */ +void inode_wait_for_writeback(struct inode *inode) +{ + spin_lock(&inode->i_lock); + __inode_wait_for_writeback(inode); + spin_unlock(&inode->i_lock); +} + +/* + * Sleep until I_SYNC is cleared. This function must be called with i_lock + * held and drops it. It is aimed for callers not holding any inode reference + * so once i_lock is dropped, inode can go away. + */ +static void inode_sleep_on_writeback(struct inode *inode) + __releases(inode->i_lock) +{ + DEFINE_WAIT(wait); + wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); + int sleep; + + prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); + sleep = inode->i_state & I_SYNC; + spin_unlock(&inode->i_lock); + if (sleep) + schedule(); + finish_wait(wqh, &wait); +} + +/* * Find proper writeback list for the inode depending on its current state and * possibly also change of its state while we were doing writeback. Here we * handle things such as livelock prevention or fairness of writeback among @@ -479,9 +512,11 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, if (wbc->sync_mode != WB_SYNC_ALL) goto out; /* - * It's a data-integrity sync. We must wait. + * It's a data-integrity sync. We must wait. Since callers hold + * inode reference or inode has I_WILL_FREE set, it cannot go + * away under us. */ - inode_wait_for_writeback(inode); + __inode_wait_for_writeback(inode); } WARN_ON(inode->i_state & I_SYNC); /* @@ -620,20 +655,28 @@ static long writeback_sb_inodes(struct super_block *sb, } spin_unlock(&wb->list_lock); - __iget(inode); /* * We already requeued the inode if it had I_SYNC set and we * are doing WB_SYNC_NONE writeback. So this catches only the * WB_SYNC_ALL case. */ - if (inode->i_state & I_SYNC) - inode_wait_for_writeback(inode); + if (inode->i_state & I_SYNC) { + /* Wait for I_SYNC. This function drops i_lock... */ + inode_sleep_on_writeback(inode); + /* Inode may be gone, start again */ + continue; + } inode->i_state |= I_SYNC; spin_unlock(&inode->i_lock); + write_chunk = writeback_chunk_size(wb->bdi, work); wbc.nr_to_write = write_chunk; wbc.pages_skipped = 0; + /* + * We use I_SYNC to pin the inode in memory. While it is set + * evict_inode() will wait so the inode cannot be freed. + */ __writeback_single_inode(inode, wb, &wbc); work->nr_pages -= write_chunk - wbc.nr_to_write; @@ -645,10 +688,7 @@ static long writeback_sb_inodes(struct super_block *sb, requeue_inode(inode, wb, &wbc); inode_sync_complete(inode); spin_unlock(&inode->i_lock); - spin_unlock(&wb->list_lock); - iput(inode); - cond_resched(); - spin_lock(&wb->list_lock); + cond_resched_lock(&wb->list_lock); /* * bail out to wb_writeback() often enough to check * background threshold and other termination conditions. @@ -843,8 +883,8 @@ static long wb_writeback(struct bdi_writeback *wb, inode = wb_inode(wb->b_more_io.prev); spin_lock(&inode->i_lock); spin_unlock(&wb->list_lock); - inode_wait_for_writeback(inode); - spin_unlock(&inode->i_lock); + /* This function drops i_lock... */ + inode_sleep_on_writeback(inode); spin_lock(&wb->list_lock); } } diff --git a/fs/inode.c b/fs/inode.c index 02c0fa5e16a4..f4e145016611 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -530,7 +530,13 @@ static void evict(struct inode *inode) inode_sb_list_del(inode); - inode_sync_wait(inode); + /* + * Wait for flusher thread to be done with the inode so that filesystem + * does not start destroying it while writeback is still running. Since + * the inode has I_FREEING set, flusher thread won't start new work on + * the inode. We just have to wait for running writeback to finish. + */ + inode_wait_for_writeback(inode); if (op->evict_inode) { op->evict_inode(inode); diff --git a/include/linux/fs.h b/include/linux/fs.h index c79316c79ee3..1c71e7f4d234 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1753,9 +1753,10 @@ struct super_operations { * anew. Other functions will just ignore such inodes, * if appropriate. I_NEW is used for waiting. * - * I_SYNC Synchonized write of dirty inode data. The bits is - * set during data writeback, and cleared with a wakeup - * on the bit address once it is done. + * I_SYNC Writeback of inode is running. The bit is set during + * data writeback, and cleared with a wakeup on the bit + * address once it is done. The bit is also used to pin + * the inode in memory for flusher thread. * * I_REFERENCED Marks the inode as recently references on the LRU list. * diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 3309736ff059..6d0a0fcd80e7 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -95,6 +95,7 @@ long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, enum wb_reason reason); long wb_do_writeback(struct bdi_writeback *wb, int force_wait); void wakeup_flusher_threads(long nr_pages, enum wb_reason reason); +void inode_wait_for_writeback(struct inode *inode); /* writeback.h requires fs.h; it, too, is not included from here. */ static inline void wait_on_inode(struct inode *inode) @@ -102,12 +103,6 @@ static inline void wait_on_inode(struct inode *inode) might_sleep(); wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); } -static inline void inode_sync_wait(struct inode *inode) -{ - might_sleep(); - wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, - TASK_UNINTERRUPTIBLE); -} /* |