ceph: use i_ceph_lock instead of i_lock

We have been using i_lock to protect all kinds of data structures in the
ceph_inode_info struct, including lists of inodes that we need to iterate
over while avoiding races with inode destruction.  That requires grabbing
a reference to the inode with the list lock protected, but igrab() now
takes i_lock to check the inode flags.

Changing the list lock ordering would be a painful process.

However, using a ceph-specific i_ceph_lock in the ceph inode instead of
i_lock is a simple mechanical change and avoids the ordering constraints
imposed by igrab().

Reported-by: Amon Ott <a.ott@m-privacy.de>
Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 28 insertions, 25 deletions

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 116f36502f1..87fb132fb33 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -297,6 +297,8 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
 
 	dout("alloc_inode %p\n", &ci->vfs_inode);
 
+	spin_lock_init(&ci->i_ceph_lock);
+
 	ci->i_version = 0;
 	ci->i_time_warp_seq = 0;
 	ci->i_ceph_flags = 0;
@@ -583,7 +585,7 @@ static int fill_inode(struct inode *inode,
 			       iinfo->xattr_len);
 	}
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 
 	/*
 	 * provided version will be odd if inode value is projected,
@@ -680,7 +682,7 @@ static int fill_inode(struct inode *inode,
 			char *sym;
 
 			BUG_ON(symlen != inode->i_size);
-			spin_unlock(&inode->i_lock);
+			spin_unlock(&ci->i_ceph_lock);
 
 			err = -ENOMEM;
 			sym = kmalloc(symlen+1, GFP_NOFS);
@@ -689,7 +691,7 @@ static int fill_inode(struct inode *inode,
 			memcpy(sym, iinfo->symlink, symlen);
 			sym[symlen] = 0;
 
-			spin_lock(&inode->i_lock);
+			spin_lock(&ci->i_ceph_lock);
 			if (!ci->i_symlink)
 				ci->i_symlink = sym;
 			else
@@ -715,7 +717,7 @@ static int fill_inode(struct inode *inode,
 	}
 
 no_change:
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 
 	/* queue truncate if we saw i_size decrease */
 	if (queue_trunc)
@@ -750,13 +752,13 @@ no_change:
 				     info->cap.flags,
 				     caps_reservation);
 		} else {
-			spin_lock(&inode->i_lock);
+			spin_lock(&ci->i_ceph_lock);
 			dout(" %p got snap_caps %s\n", inode,
 			     ceph_cap_string(le32_to_cpu(info->cap.caps)));
 			ci->i_snap_caps |= le32_to_cpu(info->cap.caps);
 			if (cap_fmode >= 0)
 				__ceph_get_fmode(ci, cap_fmode);
-			spin_unlock(&inode->i_lock);
+			spin_unlock(&ci->i_ceph_lock);
 		}
 	} else if (cap_fmode >= 0) {
 		pr_warning("mds issued no caps on %llx.%llx\n",
@@ -849,19 +851,20 @@ static void ceph_set_dentry_offset(struct dentry *dn)
 {
 	struct dentry *dir = dn->d_parent;
 	struct inode *inode = dir->d_inode;
+	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_dentry_info *di;
 
 	BUG_ON(!inode);
 
 	di = ceph_dentry(dn);
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 	if (!ceph_dir_test_complete(inode)) {
-		spin_unlock(&inode->i_lock);
+		spin_unlock(&ci->i_ceph_lock);
 		return;
 	}
 	di->offset = ceph_inode(inode)->i_max_offset++;
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 
 	spin_lock(&dir->d_lock);
 	spin_lock_nested(&dn->d_lock, DENTRY_D_LOCK_NESTED);
@@ -1308,7 +1311,7 @@ int ceph_inode_set_size(struct inode *inode, loff_t size)
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int ret = 0;
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 	dout("set_size %p %llu -> %llu\n", inode, inode->i_size, size);
 	inode->i_size = size;
 	inode->i_blocks = (size + (1 << 9) - 1) >> 9;
@@ -1318,7 +1321,7 @@ int ceph_inode_set_size(struct inode *inode, loff_t size)
 	    (ci->i_reported_size << 1) < ci->i_max_size)
 		ret = 1;
 
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 	return ret;
 }
 
@@ -1376,20 +1379,20 @@ static void ceph_invalidate_work(struct work_struct *work)
 	u32 orig_gen;
 	int check = 0;
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 	dout("invalidate_pages %p gen %d revoking %d\n", inode,
 	     ci->i_rdcache_gen, ci->i_rdcache_revoking);
 	if (ci->i_rdcache_revoking != ci->i_rdcache_gen) {
 		/* nevermind! */
-		spin_unlock(&inode->i_lock);
+		spin_unlock(&ci->i_ceph_lock);
 		goto out;
 	}
 	orig_gen = ci->i_rdcache_gen;
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 
 	truncate_inode_pages(&inode->i_data, 0);
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 	if (orig_gen == ci->i_rdcache_gen &&
 	    orig_gen == ci->i_rdcache_revoking) {
 		dout("invalidate_pages %p gen %d successful\n", inode,
@@ -1401,7 +1404,7 @@ static void ceph_invalidate_work(struct work_struct *work)
 		     inode, orig_gen, ci->i_rdcache_gen,
 		     ci->i_rdcache_revoking);
 	}
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 
 	if (check)
 		ceph_check_caps(ci, 0, NULL);
@@ -1460,10 +1463,10 @@ void __ceph_do_pending_vmtruncate(struct inode *inode)
 	int wrbuffer_refs, wake = 0;
 
 retry:
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 	if (ci->i_truncate_pending == 0) {
 		dout("__do_pending_vmtruncate %p none pending\n", inode);
-		spin_unlock(&inode->i_lock);
+		spin_unlock(&ci->i_ceph_lock);
 		return;
 	}
 
@@ -1474,7 +1477,7 @@ retry:
 	if (ci->i_wrbuffer_ref_head < ci->i_wrbuffer_ref) {
 		dout("__do_pending_vmtruncate %p flushing snaps first\n",
 		     inode);
-		spin_unlock(&inode->i_lock);
+		spin_unlock(&ci->i_ceph_lock);
 		filemap_write_and_wait_range(&inode->i_data, 0,
 					     inode->i_sb->s_maxbytes);
 		goto retry;
@@ -1484,15 +1487,15 @@ retry:
 	wrbuffer_refs = ci->i_wrbuffer_ref;
 	dout("__do_pending_vmtruncate %p (%d) to %lld\n", inode,
 	     ci->i_truncate_pending, to);
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 
 	truncate_inode_pages(inode->i_mapping, to);
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 	ci->i_truncate_pending--;
 	if (ci->i_truncate_pending == 0)
 		wake = 1;
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 
 	if (wrbuffer_refs == 0)
 		ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
@@ -1547,7 +1550,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ci->i_ceph_lock);
 	issued = __ceph_caps_issued(ci, NULL);
 	dout("setattr %p issued %s\n", inode, ceph_cap_string(issued));
 
@@ -1695,7 +1698,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	}
 
 	release &= issued;
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 
 	if (inode_dirty_flags)
 		__mark_inode_dirty(inode, inode_dirty_flags);
@@ -1717,7 +1720,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	__ceph_do_pending_vmtruncate(inode);
 	return err;
 out:
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ci->i_ceph_lock);
 	ceph_mdsc_put_request(req);
 	return err;
 }