From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757104Ab0J0XDK (ORCPT ); Wed, 27 Oct 2010 19:03:10 -0400 Received: from bld-mail12.adl6.internode.on.net ([150.101.137.97]:44594 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755440Ab0J0XDF (ORCPT ); Wed, 27 Oct 2010 19:03:05 -0400 From: Dave Chinner To: viro@ZenIV.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/4] fs: protect inode->i_state with inode->i_lock Date: Thu, 28 Oct 2010 10:02:15 +1100 Message-Id: <1288220538-21476-2-git-send-email-david@fromorbit.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1288220538-21476-1-git-send-email-david@fromorbit.com> References: <1288220538-21476-1-git-send-email-david@fromorbit.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Chinner Protect inode state transitions and validity checks with the inode->i_lock. This enables us to make inode state transitions independently of the inode_lock and is the first step to peeling away the inode_lock from the code. This requires that __iget() is done atomically with i_state checks during list traversals so that we don't race with another thread marking the inode I_FREEING between the state check and grabbing the reference. Signed-off-by: Dave Chinner --- fs/drop_caches.c | 9 +++-- fs/fs-writeback.c | 42 +++++++++++++++++----- fs/inode.c | 93 +++++++++++++++++++++++++++++++++++++++-------- fs/notify/inode_mark.c | 21 ++++++++--- fs/quota/dquot.c | 13 ++++--- 5 files changed, 138 insertions(+), 40 deletions(-) diff --git a/fs/drop_caches.c b/fs/drop_caches.c index 2195c21..62dd8ee 100644 --- a/fs/drop_caches.c +++ b/fs/drop_caches.c @@ -18,11 +18,14 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused) spin_lock(&inode_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { - if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) - continue; - if (inode->i_mapping->nrpages == 0) + spin_lock(&inode->i_lock); + if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || + (inode->i_mapping->nrpages == 0)) { + spin_unlock(&inode->i_lock); continue; + } __iget(inode); + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); invalidate_mapping_pages(inode->i_mapping, 0, -1); iput(toput_inode); diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index f6af81a..50de4f1 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -293,9 +293,11 @@ static void inode_wait_for_writeback(struct inode *inode) wqh = bit_waitqueue(&inode->i_state, __I_SYNC); while (inode->i_state & I_SYNC) { + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); spin_lock(&inode_lock); + spin_lock(&inode->i_lock); } } @@ -319,6 +321,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) unsigned dirty; int ret; + spin_lock(&inode->i_lock); if (!atomic_read(&inode->i_count)) WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); else @@ -334,6 +337,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * completed a full scan of b_io. */ if (wbc->sync_mode != WB_SYNC_ALL) { + spin_unlock(&inode->i_lock); requeue_io(inode); return 0; } @@ -349,6 +353,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) /* Set I_SYNC, reset I_DIRTY_PAGES */ inode->i_state |= I_SYNC; inode->i_state &= ~I_DIRTY_PAGES; + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); ret = do_writepages(mapping, wbc); @@ -370,8 +375,10 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * write_inode() */ spin_lock(&inode_lock); + spin_lock(&inode->i_lock); dirty = inode->i_state & I_DIRTY; inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); /* Don't write the inode if only I_DIRTY_PAGES was set */ if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { @@ -381,6 +388,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) } spin_lock(&inode_lock); + spin_lock(&inode->i_lock); inode->i_state &= ~I_SYNC; if (!(inode->i_state & I_FREEING)) { if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { @@ -422,6 +430,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) } } inode_sync_complete(inode); + spin_unlock(&inode->i_lock); return ret; } @@ -492,7 +501,9 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, * kind does not need peridic writeout yet, and for the latter * kind writeout is handled by the freer. */ + spin_lock(&inode->i_lock); if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { + spin_unlock(&inode->i_lock); requeue_io(inode); continue; } @@ -501,10 +512,14 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, * Was this inode dirtied after sync_sb_inodes was called? * This keeps sync from extra jobs and livelock. */ - if (inode_dirtied_after(inode, wbc->wb_start)) + if (inode_dirtied_after(inode, wbc->wb_start)) { + spin_unlock(&inode->i_lock); return 1; + } __iget(inode); + spin_unlock(&inode->i_lock); + pages_skipped = wbc->pages_skipped; writeback_single_inode(inode, wbc); if (wbc->pages_skipped != pages_skipped) { @@ -681,7 +696,9 @@ static long wb_writeback(struct bdi_writeback *wb, if (!list_empty(&wb->b_more_io)) { inode = wb_inode(wb->b_more_io.prev); trace_wbc_writeback_wait(&wbc, wb->bdi); + spin_lock(&inode->i_lock); inode_wait_for_writeback(inode); + spin_unlock(&inode->i_lock); } spin_unlock(&inode_lock); } @@ -947,6 +964,7 @@ void __mark_inode_dirty(struct inode *inode, int flags) block_dump___mark_inode_dirty(inode); spin_lock(&inode_lock); + spin_lock(&inode->i_lock); if ((inode->i_state & flags) != flags) { const int was_dirty = inode->i_state & I_DIRTY; @@ -958,7 +976,7 @@ void __mark_inode_dirty(struct inode *inode, int flags) * superblock list, based upon its state. */ if (inode->i_state & I_SYNC) - goto out; + goto out_unlock_inode; /* * Only add valid (hashed) inodes to the superblock's @@ -966,11 +984,12 @@ void __mark_inode_dirty(struct inode *inode, int flags) */ if (!S_ISBLK(inode->i_mode)) { if (inode_unhashed(inode)) - goto out; + goto out_unlock_inode; } if (inode->i_state & I_FREEING) - goto out; + goto out_unlock_inode; + spin_unlock(&inode->i_lock); /* * If the inode was already on b_dirty/b_io/b_more_io, don't * reposition it (that would break b_dirty time-ordering). @@ -995,7 +1014,10 @@ void __mark_inode_dirty(struct inode *inode, int flags) inode->dirtied_when = jiffies; list_move(&inode->i_wb_list, &bdi->wb.b_dirty); } + goto out; } +out_unlock_inode: + spin_unlock(&inode->i_lock); out: spin_unlock(&inode_lock); @@ -1041,14 +1063,16 @@ static void wait_sb_inodes(struct super_block *sb) * we still have to wait for that writeout. */ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { - struct address_space *mapping; + struct address_space *mapping = inode->i_mapping; - if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) - continue; - mapping = inode->i_mapping; - if (mapping->nrpages == 0) + spin_lock(&inode->i_lock); + if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || + (mapping->nrpages == 0)) { + spin_unlock(&inode->i_lock); continue; + } __iget(inode); + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); /* * We hold a reference to 'inode' so it couldn't have diff --git a/fs/inode.c b/fs/inode.c index a6d6068..e1959f3 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -26,6 +26,17 @@ #include /* + * inode locking rules. + * + * inode->i_lock protects: + * inode->i_state, __iget() + * + * Lock ordering: + * inode_lock + * inode->i_lock + */ + +/* * This is needed for the following functions: * - inode_has_buffers * - invalidate_bdev @@ -429,7 +440,9 @@ void end_writeback(struct inode *inode) BUG_ON(!(inode->i_state & I_FREEING)); BUG_ON(inode->i_state & I_CLEAR); inode_sync_wait(inode); + spin_lock(&inode->i_lock); inode->i_state = I_FREEING | I_CLEAR; + spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(end_writeback); @@ -498,12 +511,17 @@ void evict_inodes(struct super_block *sb) if (atomic_read(&inode->i_count)) continue; + spin_lock(&inode->i_lock); if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { + spin_unlock(&inode->i_lock); WARN_ON(1); continue; } inode->i_state |= I_FREEING; + if (!(inode->i_state & (I_DIRTY | I_SYNC))) + percpu_counter_dec(&nr_inodes_unused); + spin_unlock(&inode->i_lock); /* * Move the inode off the IO lists and LRU once I_FREEING is @@ -511,8 +529,6 @@ void evict_inodes(struct super_block *sb) */ list_move(&inode->i_lru, &dispose); list_del_init(&inode->i_wb_list); - if (!(inode->i_state & (I_DIRTY | I_SYNC))) - percpu_counter_dec(&nr_inodes_unused); } spin_unlock(&inode_lock); @@ -537,14 +553,21 @@ int invalidate_inodes(struct super_block *sb) spin_lock(&inode_lock); list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) { - if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) + spin_lock(&inode->i_lock); + if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { + spin_unlock(&inode->i_lock); continue; + } if (atomic_read(&inode->i_count)) { + spin_unlock(&inode->i_lock); busy = 1; continue; } inode->i_state |= I_FREEING; + if (!(inode->i_state & (I_DIRTY | I_SYNC))) + percpu_counter_dec(&nr_inodes_unused); + spin_unlock(&inode->i_lock); /* * Move the inode off the IO lists and LRU once I_FREEING is @@ -552,8 +575,6 @@ int invalidate_inodes(struct super_block *sb) */ list_move(&inode->i_lru, &dispose); list_del_init(&inode->i_wb_list); - if (!(inode->i_state & (I_DIRTY | I_SYNC))) - percpu_counter_dec(&nr_inodes_unused); } spin_unlock(&inode_lock); @@ -612,8 +633,10 @@ static void prune_icache(int nr_to_scan) * Referenced or dirty inodes are still in use. Give them * another pass through the LRU as we canot reclaim them now. */ + spin_lock(&inode->i_lock); if (atomic_read(&inode->i_count) || (inode->i_state & ~I_REFERENCED)) { + spin_unlock(&inode->i_lock); list_del_init(&inode->i_lru); percpu_counter_dec(&nr_inodes_unused); continue; @@ -621,12 +644,14 @@ static void prune_icache(int nr_to_scan) /* recently referenced inodes get one more pass */ if (inode->i_state & I_REFERENCED) { - list_move(&inode->i_lru, &inode_lru); inode->i_state &= ~I_REFERENCED; + spin_unlock(&inode->i_lock); + list_move(&inode->i_lru, &inode_lru); continue; } if (inode_has_buffers(inode) || inode->i_data.nrpages) { __iget(inode); + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); if (remove_inode_buffers(inode)) reap += invalidate_mapping_pages(&inode->i_data, @@ -637,11 +662,15 @@ static void prune_icache(int nr_to_scan) if (inode != list_entry(inode_lru.next, struct inode, i_lru)) continue; /* wrong inode or list_empty */ - if (!can_unuse(inode)) + spin_lock(&inode->i_lock); + if (!can_unuse(inode)) { + spin_unlock(&inode->i_lock); continue; + } } WARN_ON(inode->i_state & I_NEW); inode->i_state |= I_FREEING; + spin_unlock(&inode->i_lock); /* * Move the inode off the IO lists and LRU once I_FREEING is @@ -708,11 +737,13 @@ repeat: continue; if (!test(inode, data)) continue; + spin_lock(&inode->i_lock); if (inode->i_state & (I_FREEING|I_WILL_FREE)) { __wait_on_freeing_inode(inode); goto repeat; } __iget(inode); + spin_unlock(&inode->i_lock); return inode; } return NULL; @@ -734,11 +765,13 @@ repeat: continue; if (inode->i_sb != sb) continue; + spin_lock(&inode->i_lock); if (inode->i_state & (I_FREEING|I_WILL_FREE)) { __wait_on_freeing_inode(inode); goto repeat; } __iget(inode); + spin_unlock(&inode->i_lock); return inode; } return NULL; @@ -803,8 +836,10 @@ struct inode *new_inode(struct super_block *sb) inode = alloc_inode(sb); if (inode) { spin_lock(&inode_lock); - __inode_sb_list_add(inode); + spin_lock(&inode->i_lock); inode->i_state = 0; + spin_unlock(&inode->i_lock); + __inode_sb_list_add(inode); spin_unlock(&inode_lock); } return inode; @@ -871,9 +906,11 @@ static struct inode *get_new_inode(struct super_block *sb, if (set(inode, data)) goto set_failed; + spin_lock(&inode->i_lock); + inode->i_state = I_NEW; + spin_unlock(&inode->i_lock); hlist_add_head(&inode->i_hash, head); __inode_sb_list_add(inode); - inode->i_state = I_NEW; spin_unlock(&inode_lock); /* Return the locked inode with I_NEW set, the @@ -917,10 +954,12 @@ static struct inode *get_new_inode_fast(struct super_block *sb, /* We released the lock, so.. */ old = find_inode_fast(sb, head, ino); if (!old) { + spin_lock(&inode->i_lock); inode->i_ino = ino; + inode->i_state = I_NEW; + spin_unlock(&inode->i_lock); hlist_add_head(&inode->i_hash, head); __inode_sb_list_add(inode); - inode->i_state = I_NEW; spin_unlock(&inode_lock); /* Return the locked inode with I_NEW set, the @@ -1005,15 +1044,19 @@ EXPORT_SYMBOL(iunique); struct inode *igrab(struct inode *inode) { spin_lock(&inode_lock); - if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) + spin_lock(&inode->i_lock); + if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) { __iget(inode); - else + spin_unlock(&inode->i_lock); + } else { + spin_unlock(&inode->i_lock); /* * Handle the case where s_op->clear_inode is not been * called yet, and somebody is calling igrab * while the inode is getting freed. */ inode = NULL; + } spin_unlock(&inode_lock); return inode; } @@ -1242,7 +1285,9 @@ int insert_inode_locked(struct inode *inode) ino_t ino = inode->i_ino; struct hlist_head *head = inode_hashtable + hash(sb, ino); + spin_lock(&inode->i_lock); inode->i_state |= I_NEW; + spin_unlock(&inode->i_lock); while (1) { struct hlist_node *node; struct inode *old = NULL; @@ -1252,8 +1297,11 @@ int insert_inode_locked(struct inode *inode) continue; if (old->i_sb != sb) continue; - if (old->i_state & (I_FREEING|I_WILL_FREE)) + spin_lock(&old->i_lock); + if (old->i_state & (I_FREEING|I_WILL_FREE)) { + spin_unlock(&old->i_lock); continue; + } break; } if (likely(!node)) { @@ -1262,6 +1310,7 @@ int insert_inode_locked(struct inode *inode) return 0; } __iget(old); + spin_unlock(&old->i_lock); spin_unlock(&inode_lock); wait_on_inode(old); if (unlikely(!inode_unhashed(old))) { @@ -1279,7 +1328,9 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval, struct super_block *sb = inode->i_sb; struct hlist_head *head = inode_hashtable + hash(sb, hashval); + spin_lock(&inode->i_lock); inode->i_state |= I_NEW; + spin_unlock(&inode->i_lock); while (1) { struct hlist_node *node; @@ -1291,8 +1342,11 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval, continue; if (!test(old, data)) continue; - if (old->i_state & (I_FREEING|I_WILL_FREE)) + spin_lock(&old->i_lock); + if (old->i_state & (I_FREEING|I_WILL_FREE)) { + spin_unlock(&old->i_lock); continue; + } break; } if (likely(!node)) { @@ -1301,6 +1355,7 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval, return 0; } __iget(old); + spin_unlock(&old->i_lock); spin_unlock(&inode_lock); wait_on_inode(old); if (unlikely(!inode_unhashed(old))) { @@ -1346,6 +1401,9 @@ static void iput_final(struct inode *inode) const struct super_operations *op = inode->i_sb->s_op; int drop; + spin_lock(&inode->i_lock); + WARN_ON(inode->i_state & I_NEW); + if (op && op->drop_inode) drop = op->drop_inode(inode); else @@ -1357,21 +1415,23 @@ static void iput_final(struct inode *inode) if (!(inode->i_state & (I_DIRTY|I_SYNC))) { inode_lru_list_add(inode); } + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); return; } - WARN_ON(inode->i_state & I_NEW); inode->i_state |= I_WILL_FREE; + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); write_inode_now(inode, 1); spin_lock(&inode_lock); + spin_lock(&inode->i_lock); WARN_ON(inode->i_state & I_NEW); inode->i_state &= ~I_WILL_FREE; __remove_inode_hash(inode); } - WARN_ON(inode->i_state & I_NEW); inode->i_state |= I_FREEING; + spin_unlock(&inode->i_lock); /* * Move the inode off the IO lists and LRU once I_FREEING is @@ -1592,6 +1652,7 @@ static void __wait_on_freeing_inode(struct inode *inode) DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW); wq = bit_waitqueue(&inode->i_state, __I_NEW); prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE); + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); schedule(); finish_wait(wq, &wait.wait); diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c index 21ed106..9c0fb09 100644 --- a/fs/notify/inode_mark.c +++ b/fs/notify/inode_mark.c @@ -249,8 +249,11 @@ void fsnotify_unmount_inodes(struct list_head *list) * I_WILL_FREE, or I_NEW which is fine because by that point * the inode cannot have any associated watches. */ - if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) + spin_lock(&inode->i_lock); + if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { + spin_unlock(&inode->i_lock); continue; + } /* * If i_count is zero, the inode cannot have any watches and @@ -258,8 +261,10 @@ void fsnotify_unmount_inodes(struct list_head *list) * evict all inodes with zero i_count from icache which is * unnecessarily violent and may in fact be illegal to do. */ - if (!atomic_read(&inode->i_count)) + if (!atomic_read(&inode->i_count)) { + spin_unlock(&inode->i_lock); continue; + } need_iput_tmp = need_iput; need_iput = NULL; @@ -269,13 +274,17 @@ void fsnotify_unmount_inodes(struct list_head *list) __iget(inode); else need_iput_tmp = NULL; + spin_unlock(&inode->i_lock); /* In case the dropping of a reference would nuke next_i. */ if ((&next_i->i_sb_list != list) && - atomic_read(&next_i->i_count) && - !(next_i->i_state & (I_FREEING | I_WILL_FREE))) { - __iget(next_i); - need_iput = next_i; + atomic_read(&next_i->i_count)) { + spin_lock(&next_i->i_lock); + if (!(next_i->i_state & (I_FREEING | I_WILL_FREE))) { + __iget(next_i); + need_iput = next_i; + } + spin_unlock(&next_i->i_lock); } /* diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index aad1316..a2d89f8 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -898,18 +898,19 @@ static void add_dquot_ref(struct super_block *sb, int type) spin_lock(&inode_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { - if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) + spin_lock(&inode->i_lock); + if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || + !atomic_read(&inode->i_writecount) || + !dqinit_needed(inode, type)) { + spin_unlock(&inode->i_lock); continue; + } #ifdef CONFIG_QUOTA_DEBUG if (unlikely(inode_get_rsv_space(inode) > 0)) reserved = 1; #endif - if (!atomic_read(&inode->i_writecount)) - continue; - if (!dqinit_needed(inode, type)) - continue; - __iget(inode); + spin_unlock(&inode->i_lock); spin_unlock(&inode_lock); iput(old_inode); -- 1.7.1