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authorThomas Betker <thomas.betker@rohde-schwarz.com>2015-11-10 22:18:15 +0100
committerSasha Levin <sasha.levin@oracle.com>2016-03-09 13:15:06 -0500
commit74d11976ff45dfe15b8a965d72237ac98533f788 (patch)
treef5c08f87f952de7e18ab0f808511308578e26f4a
parent79e6eddd93bc3dfa020a57886d666dea9b9f452e (diff)
Revert "jffs2: Fix lock acquisition order bug in jffs2_write_begin"
[ Upstream commit 157078f64b8a9cd7011b6b900b2f2498df850748 ] 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 <deng.chao1@zte.com.cn> Reported-by: Ming Liu <liu.ming50@gmail.com> Reported-by: wangzaiwei <wangzaiwei@top-vision.cn> Signed-off-by: Thomas Betker <thomas.betker@rohde-schwarz.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--fs/jffs2/file.c39
1 files changed, 18 insertions, 21 deletions
diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
index f509f62e12f6..3361979d728c 100644
--- a/fs/jffs2/file.c
+++ b/fs/jffs2/file.c
@@ -137,39 +137,33 @@ 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;
- jffs2_dbg(1, "%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) {
+ jffs2_dbg(1, "%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;
jffs2_dbg(1, "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);
@@ -196,6 +190,7 @@ 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);
@@ -210,10 +205,12 @@ 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);
}
/*
@@ -222,18 +219,18 @@ 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);
jffs2_dbg(1, "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;
}