GFS2: glock livelock

This patch fixes a couple gfs2 problems with the reclaiming of
unlinked dinodes.  First, there were a couple of livelocks where
everything would come to a halt waiting for a glock that was
seemingly held by a process that no longer existed.  In fact, the
process did exist, it just had the wrong pid number in the holder
information.  Second, there was a lock ordering problem between
inode locking and glock locking.  Third, glock/inode contention
could sometimes cause inodes to be improperly marked invalid by
iget_failed.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>

7 files changed, 144 insertions, 29 deletions

diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index 25fddc100f18..8295c5b5d4a9 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -1475,7 +1475,7 @@ struct inode *gfs2_dir_search(struct inode *dir, const struct qstr *name)
                 inode = gfs2_inode_lookup(dir->i_sb, 
                                 be16_to_cpu(dent->de_type),
                                 be64_to_cpu(dent->de_inum.no_addr),
-                                be64_to_cpu(dent->de_inum.no_formal_ino), 0);
+                                be64_to_cpu(dent->de_inum.no_formal_ino));
                 brelse(bh);
                 return inode;
         }
diff --git a/fs/gfs2/export.c b/fs/gfs2/export.c
index d15876e9aa26..d81bc7e90e98 100644
--- a/fs/gfs2/export.c
+++ b/fs/gfs2/export.c
@@ -169,7 +169,7 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb,
         if (error)
                 goto fail;
 
-        inode = gfs2_inode_lookup(sb, DT_UNKNOWN, inum->no_addr, 0, 0);
+        inode = gfs2_inode_lookup(sb, DT_UNKNOWN, inum->no_addr, 0);
         if (IS_ERR(inode)) {
                 error = PTR_ERR(inode);
                 goto fail;
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 454d4b4eb36b..ddcdbf493536 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -855,6 +855,9 @@ void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *
         gh->gh_flags = flags;
         gh->gh_iflags = 0;
         gh->gh_ip = (unsigned long)__builtin_return_address(0);
+        if (gh->gh_owner_pid)
+                put_pid(gh->gh_owner_pid);
+        gh->gh_owner_pid = get_pid(task_pid(current));
 }
 
 /**
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index b1bf2694fb2b..51d8061fa07a 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -158,7 +158,6 @@ void gfs2_set_iop(struct inode *inode)
  * @sb: The super block
  * @no_addr: The inode number
  * @type: The type of the inode
- * @skip_freeing: set this not return an inode if it is currently being freed.
  *
  * Returns: A VFS inode, or an error
  */
@@ -166,17 +165,14 @@ void gfs2_set_iop(struct inode *inode)
 struct inode *gfs2_inode_lookup(struct super_block *sb,
                                 unsigned int type,
                                 u64 no_addr,
-                                u64 no_formal_ino, int skip_freeing)
+                                u64 no_formal_ino)
 {
         struct inode *inode;
         struct gfs2_inode *ip;
         struct gfs2_glock *io_gl;
         int error;
 
-        if (skip_freeing)
-                inode = gfs2_iget_skip(sb, no_addr);
-        else
-                inode = gfs2_iget(sb, no_addr);
+        inode = gfs2_iget(sb, no_addr);
         ip = GFS2_I(inode);
 
         if (!inode)
@@ -234,13 +230,100 @@ fail_glock:
 fail_iopen:
         gfs2_glock_put(io_gl);
 fail_put:
-        ip->i_gl->gl_object = NULL;
+        if (inode->i_state & I_NEW)
+                ip->i_gl->gl_object = NULL;
         gfs2_glock_put(ip->i_gl);
 fail:
-        iget_failed(inode);
+        if (inode->i_state & I_NEW)
+                iget_failed(inode);
+        else
+                iput(inode);
         return ERR_PTR(error);
 }
 
+/**
+ * gfs2_unlinked_inode_lookup - Lookup an unlinked inode for reclamation
+ * @sb: The super block
+ * no_addr: The inode number
+ * @@inode: A pointer to the inode found, if any
+ *
+ * Returns: 0 and *inode if no errors occurred.  If an error occurs,
+ *          the resulting *inode may or may not be NULL.
+ */
+
+int gfs2_unlinked_inode_lookup(struct super_block *sb, u64 no_addr,
+                               struct inode **inode)
+{
+        struct gfs2_sbd *sdp;
+        struct gfs2_inode *ip;
+        struct gfs2_glock *io_gl;
+        int error;
+        struct gfs2_holder gh;
+
+        *inode = gfs2_iget_skip(sb, no_addr);
+
+        if (!(*inode))
+                return -ENOBUFS;
+
+        if (!((*inode)->i_state & I_NEW))
+                return -ENOBUFS;
+
+        ip = GFS2_I(*inode);
+        sdp = GFS2_SB(*inode);
+        ip->i_no_formal_ino = -1;
+
+        error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl);
+        if (unlikely(error))
+                goto fail;
+        ip->i_gl->gl_object = ip;
+
+        error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
+        if (unlikely(error))
+                goto fail_put;
+
+        set_bit(GIF_INVALID, &ip->i_flags);
+        error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, LM_FLAG_TRY | GL_EXACT,
+                                   &ip->i_iopen_gh);
+        if (unlikely(error)) {
+                if (error == GLR_TRYFAILED)
+                        error = 0;
+                goto fail_iopen;
+        }
+        ip->i_iopen_gh.gh_gl->gl_object = ip;
+        gfs2_glock_put(io_gl);
+
+        (*inode)->i_mode = DT2IF(DT_UNKNOWN);
+
+        /*
+         * We must read the inode in order to work out its type in
+         * this case. Note that this doesn't happen often as we normally
+         * know the type beforehand. This code path only occurs during
+         * unlinked inode recovery (where it is safe to do this glock,
+         * which is not true in the general case).
+         */
+        error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, LM_FLAG_TRY,
+                                   &gh);
+        if (unlikely(error)) {
+                if (error == GLR_TRYFAILED)
+                        error = 0;
+                goto fail_glock;
+        }
+        /* Inode is now uptodate */
+        gfs2_glock_dq_uninit(&gh);
+        gfs2_set_iop(*inode);
+
+        return 0;
+fail_glock:
+        gfs2_glock_dq(&ip->i_iopen_gh);
+fail_iopen:
+        gfs2_glock_put(io_gl);
+fail_put:
+        ip->i_gl->gl_object = NULL;
+        gfs2_glock_put(ip->i_gl);
+fail:
+        return error;
+}
+
 static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
 {
         const struct gfs2_dinode *str = buf;
@@ -862,7 +945,7 @@ struct inode *gfs2_createi(struct gfs2_holder *ghs, const struct qstr *name,
                 goto fail_gunlock2;
 
         inode = gfs2_inode_lookup(dir->i_sb, IF2DT(mode), inum.no_addr,
-                                  inum.no_formal_ino, 0);
+                                  inum.no_formal_ino);
         if (IS_ERR(inode))
                 goto fail_gunlock2;
 
diff --git a/fs/gfs2/inode.h b/fs/gfs2/inode.h
index c341aaf67adb..e161461d4c57 100644
--- a/fs/gfs2/inode.h
+++ b/fs/gfs2/inode.h
@@ -83,8 +83,9 @@ static inline void gfs2_inum_out(const struct gfs2_inode *ip,
 
 extern void gfs2_set_iop(struct inode *inode);
 extern struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned type, 
-                                       u64 no_addr, u64 no_formal_ino,
-                                       int skip_freeing);
+                                       u64 no_addr, u64 no_formal_ino);
+extern int gfs2_unlinked_inode_lookup(struct super_block *sb, u64 no_addr,
+                                      struct inode **inode);
 extern struct inode *gfs2_ilookup(struct super_block *sb, u64 no_addr);
 
 extern int gfs2_inode_refresh(struct gfs2_inode *ip);
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index c1309ed1c496..dc35f3470271 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -487,7 +487,7 @@ static int gfs2_lookup_root(struct super_block *sb, struct dentry **dptr,
         struct dentry *dentry;
         struct inode *inode;
 
-        inode = gfs2_inode_lookup(sb, DT_DIR, no_addr, 0, 0);
+        inode = gfs2_inode_lookup(sb, DT_DIR, no_addr, 0);
         if (IS_ERR(inode)) {
                 fs_err(sdp, "can't read in %s inode: %ld\n", name, PTR_ERR(inode));
                 return PTR_ERR(inode);
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 503b842f3ba2..37391550284f 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -948,18 +948,20 @@ static int try_rgrp_fit(struct gfs2_rgrpd *rgd, struct gfs2_alloc *al)
  * try_rgrp_unlink - Look for any unlinked, allocated, but unused inodes
  * @rgd: The rgrp
  *
- * Returns: The inode, if one has been found
+ * Returns: 0 if no error
+ *          The inode, if one has been found, in inode.
  */
 
-static struct inode *try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
-                                     u64 skip)
+static int try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
+                           u64 skip, struct inode **inode)
 {
-        struct inode *inode;
         u32 goal = 0, block;
         u64 no_addr;
         struct gfs2_sbd *sdp = rgd->rd_sbd;
         unsigned int n;
+        int error = 0;
 
+        *inode = NULL;
         for(;;) {
                 if (goal >= rgd->rd_data)
                         break;
@@ -979,14 +981,14 @@ static struct inode *try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
                 if (no_addr == skip)
                         continue;
                 *last_unlinked = no_addr;
-                inode = gfs2_inode_lookup(rgd->rd_sbd->sd_vfs, DT_UNKNOWN,
-                                          no_addr, -1, 1);
-                if (!IS_ERR(inode))
-                        return inode;
+                error = gfs2_unlinked_inode_lookup(rgd->rd_sbd->sd_vfs,
+                                                   no_addr, inode);
+                if (*inode || error)
+                        return error;
         }
 
         rgd->rd_flags &= ~GFS2_RDF_CHECK;
-        return NULL;
+        return 0;
 }
 
 /**
@@ -1096,12 +1098,27 @@ static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
                 case 0:
                         if (try_rgrp_fit(rgd, al))
                                 goto out;
-                        if (rgd->rd_flags & GFS2_RDF_CHECK)
-                                inode = try_rgrp_unlink(rgd, last_unlinked, ip->i_no_addr);
+                        /* If the rg came in already locked, there's no
+                           way we can recover from a failed try_rgrp_unlink
+                           because that would require an iput which can only
+                           happen after the rgrp is unlocked. */
+                        if (!rg_locked && rgd->rd_flags & GFS2_RDF_CHECK)
+                                error = try_rgrp_unlink(rgd, last_unlinked,
+                                                        ip->i_no_addr, &inode);
                         if (!rg_locked)
                                 gfs2_glock_dq_uninit(&al->al_rgd_gh);
-                        if (inode)
+                        if (inode) {
+                                if (error) {
+                                        if (inode->i_state & I_NEW)
+                                                iget_failed(inode);
+                                        else
+                                                iput(inode);
+                                        return ERR_PTR(error);
+                                }
                                 return inode;
+                        }
+                        if (error)
+                                return ERR_PTR(error);
                         /* fall through */
                 case GLR_TRYFAILED:
                         rgd = recent_rgrp_next(rgd);
@@ -1130,12 +1147,23 @@ static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
                 case 0:
                         if (try_rgrp_fit(rgd, al))
                                 goto out;
-                        if (rgd->rd_flags & GFS2_RDF_CHECK)
-                                inode = try_rgrp_unlink(rgd, last_unlinked, ip->i_no_addr);
+                        if (!rg_locked && rgd->rd_flags & GFS2_RDF_CHECK)
+                                error = try_rgrp_unlink(rgd, last_unlinked,
+                                                        ip->i_no_addr, &inode);
                         if (!rg_locked)
                                 gfs2_glock_dq_uninit(&al->al_rgd_gh);
-                        if (inode)
+                        if (inode) {
+                                if (error) {
+                                        if (inode->i_state & I_NEW)
+                                                iget_failed(inode);
+                                        else
+                                                iput(inode);
+                                        return ERR_PTR(error);
+                                }
                                 return inode;
+                        }
+                        if (error)
+                                return ERR_PTR(error);
                         break;
 
                 case GLR_TRYFAILED: