From b7289da851178cdb10e4871547c36947eccd84af Mon Sep 17 00:00:00 2001 From: Thomas Betker Date: Tue, 10 Nov 2015 22:18:15 +0100 Subject: [PATCH] Revert "jffs2: Fix lock acquisition order bug in jffs2_write_begin" commit 157078f64b8a9cd7011b6b900b2f2498df850748 upstream. This reverts commit 5ffd3412ae55 ("jffs2: Fix lock acquisition order bug in jffs2_write_begin"). The commit modified jffs2_write_begin() to remove a deadlock with jffs2_garbage_collect_live(), but this introduced new deadlocks found by multiple users. page_lock() actually has to be called before mutex_lock(&c->alloc_sem) or mutex_lock(&f->sem) because jffs2_write_end() and jffs2_readpage() are called with the page locked, and they acquire c->alloc_sem and f->sem, resp. In other words, the lock order in jffs2_write_begin() was correct, and it is the jffs2_garbage_collect_live() path that has to be changed. Revert the commit to get rid of the new deadlocks, and to clear the way for a better fix of the original deadlock. Reported-by: Deng Chao Reported-by: Ming Liu Reported-by: wangzaiwei Signed-off-by: Thomas Betker Signed-off-by: David Woodhouse [bwh: Backported to 3.2: use D1(printk(KERN_DEBUG ...)) instead of jffs2_dbg(1, ...)] Signed-off-by: Ben Hutchings --- fs/jffs2/file.c | 39 ++++++++++++++++++--------------------- 1 file changed, 18 insertions(+), 21 deletions(-) diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c index 0095a70a3426..4964a5bd2d26 100644 --- a/fs/jffs2/file.c +++ b/fs/jffs2/file.c @@ -135,39 +135,33 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping, struct page *pg; struct inode *inode = mapping->host; struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode); - struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb); - struct jffs2_raw_inode ri; - uint32_t alloc_len = 0; pgoff_t index = pos >> PAGE_CACHE_SHIFT; uint32_t pageofs = index << PAGE_CACHE_SHIFT; int ret = 0; - D1(printk(KERN_DEBUG "%s()\n", __func__)); - - if (pageofs > inode->i_size) { - ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len, - ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE); - if (ret) - return ret; - } - - mutex_lock(&f->sem); pg = grab_cache_page_write_begin(mapping, index, flags); - if (!pg) { - if (alloc_len) - jffs2_complete_reservation(c); - mutex_unlock(&f->sem); + if (!pg) return -ENOMEM; - } *pagep = pg; - if (alloc_len) { + D1(printk(KERN_DEBUG "%s()\n", __func__)); + + if (pageofs > inode->i_size) { /* Make new hole frag from old EOF to new page */ + struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb); + struct jffs2_raw_inode ri; struct jffs2_full_dnode *fn; + uint32_t alloc_len; D1(printk(KERN_DEBUG "Writing new hole frag 0x%x-0x%x between current EOF and new page\n", (unsigned int)inode->i_size, pageofs)); + ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len, + ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE); + if (ret) + goto out_page; + + mutex_lock(&f->sem); memset(&ri, 0, sizeof(ri)); ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK); @@ -194,6 +188,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping, if (IS_ERR(fn)) { ret = PTR_ERR(fn); jffs2_complete_reservation(c); + mutex_unlock(&f->sem); goto out_page; } ret = jffs2_add_full_dnode_to_inode(c, f, fn); @@ -207,10 +202,12 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping, jffs2_mark_node_obsolete(c, fn->raw); jffs2_free_full_dnode(fn); jffs2_complete_reservation(c); + mutex_unlock(&f->sem); goto out_page; } jffs2_complete_reservation(c); inode->i_size = pageofs; + mutex_unlock(&f->sem); } /* @@ -219,18 +216,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping, * case of a short-copy. */ if (!PageUptodate(pg)) { + mutex_lock(&f->sem); ret = jffs2_do_readpage_nolock(inode, pg); + mutex_unlock(&f->sem); if (ret) goto out_page; } - mutex_unlock(&f->sem); D1(printk(KERN_DEBUG "end write_begin(). pg->flags %lx\n", pg->flags)); return ret; out_page: unlock_page(pg); page_cache_release(pg); - mutex_unlock(&f->sem); return ret; } -- 2.39.2