GFS2: filesystem hang caused by incorrect lock order
This patch fixes a deadlock in GFS2 where two processes are trying
to reclaim an unlinked dinode:
One holds the inode glock and calls gfs2_lookup_by_inum trying to look
up the inode, which it can't, due to I_FREEING. The other has set
I_FREEING from vfs and is at the beginning of gfs2_delete_inode
waiting for the glock, which is held by the first. The solution is to
add a new non_block parameter to the gfs2_iget function that causes it
to return -ENOENT if the inode is being freed.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 97d54a2..9134dcb 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -40,37 +40,61 @@
u64 ir_length;
};
+struct gfs2_skip_data {
+ u64 no_addr;
+ int skipped;
+ int non_block;
+};
+
static int iget_test(struct inode *inode, void *opaque)
{
struct gfs2_inode *ip = GFS2_I(inode);
- u64 *no_addr = opaque;
+ struct gfs2_skip_data *data = opaque;
- if (ip->i_no_addr == *no_addr)
+ if (ip->i_no_addr == data->no_addr) {
+ if (data->non_block &&
+ inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
+ data->skipped = 1;
+ return 0;
+ }
return 1;
-
+ }
return 0;
}
static int iget_set(struct inode *inode, void *opaque)
{
struct gfs2_inode *ip = GFS2_I(inode);
- u64 *no_addr = opaque;
+ struct gfs2_skip_data *data = opaque;
- inode->i_ino = (unsigned long)*no_addr;
- ip->i_no_addr = *no_addr;
+ if (data->skipped)
+ return -ENOENT;
+ inode->i_ino = (unsigned long)(data->no_addr);
+ ip->i_no_addr = data->no_addr;
return 0;
}
struct inode *gfs2_ilookup(struct super_block *sb, u64 no_addr)
{
unsigned long hash = (unsigned long)no_addr;
- return ilookup5(sb, hash, iget_test, &no_addr);
+ struct gfs2_skip_data data;
+
+ data.no_addr = no_addr;
+ data.skipped = 0;
+ data.non_block = 0;
+ return ilookup5(sb, hash, iget_test, &data);
}
-static struct inode *gfs2_iget(struct super_block *sb, u64 no_addr)
+static struct inode *gfs2_iget(struct super_block *sb, u64 no_addr,
+ int non_block)
{
+ struct gfs2_skip_data data;
unsigned long hash = (unsigned long)no_addr;
- return iget5_locked(sb, hash, iget_test, iget_set, &no_addr);
+
+ data.no_addr = no_addr;
+ data.skipped = 0;
+ data.non_block = non_block;
+ return iget5_locked(sb, hash, iget_test, iget_set, &data);
}
/**
@@ -111,19 +135,20 @@
* @sb: The super block
* @no_addr: The inode number
* @type: The type of the inode
+ * non_block: Can we block on inodes that are being freed?
*
* Returns: A VFS inode, or an error
*/
struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
- u64 no_addr, u64 no_formal_ino)
+ u64 no_addr, u64 no_formal_ino, int non_block)
{
struct inode *inode;
struct gfs2_inode *ip;
struct gfs2_glock *io_gl = NULL;
int error;
- inode = gfs2_iget(sb, no_addr);
+ inode = gfs2_iget(sb, no_addr, non_block);
ip = GFS2_I(inode);
if (!inode)
@@ -185,11 +210,12 @@
{
struct super_block *sb = sdp->sd_vfs;
struct gfs2_holder i_gh;
- struct inode *inode;
+ struct inode *inode = NULL;
int error;
+ /* Must not read in block until block type is verified */
error = gfs2_glock_nq_num(sdp, no_addr, &gfs2_inode_glops,
- LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
+ LM_ST_EXCLUSIVE, GL_SKIP, &i_gh);
if (error)
return ERR_PTR(error);
@@ -197,7 +223,7 @@
if (error)
goto fail;
- inode = gfs2_inode_lookup(sb, DT_UNKNOWN, no_addr, 0);
+ inode = gfs2_inode_lookup(sb, DT_UNKNOWN, no_addr, 0, 1);
if (IS_ERR(inode))
goto fail;
@@ -843,7 +869,7 @@
goto fail_gunlock2;
inode = gfs2_inode_lookup(dir->i_sb, IF2DT(mode), inum.no_addr,
- inum.no_formal_ino);
+ inum.no_formal_ino, 0);
if (IS_ERR(inode))
goto fail_gunlock2;