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Go Back   Linux Archive > Redhat > Cluster Development

 
 
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Old 04-19-2011, 08:40 AM
Steven Whitehouse
 
Default GFS2: filesystem hang caused by incorrect lock order

From: Bob Peterson <rpeterso@redhat.com>

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/dir.c b/fs/gfs2/dir.c
index 5c356d0..f789c57 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -1506,7 +1506,7 @@ 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));
+ be64_to_cpu(dent->de_inum.no_formal_ino), 0);
brelse(bh);
return inode;
}
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 @@ struct gfs2_inum_range_host {
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 @@ static void gfs2_set_iop(struct inode *inode)
* @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 inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
{
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 @@ struct inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
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 @@ 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);
+ inum.no_formal_ino, 0);
if (IS_ERR(inode))
goto fail_gunlock2;

diff --git a/fs/gfs2/inode.h b/fs/gfs2/inode.h
index 3e00a66..099ca30 100644
--- a/fs/gfs2/inode.h
+++ b/fs/gfs2/inode.h
@@ -97,7 +97,8 @@ err:
}

extern struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned type,
- u64 no_addr, u64 no_formal_ino);
+ u64 no_addr, u64 no_formal_ino,
+ int non_block);
extern struct inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
u64 *no_formal_ino,
unsigned int blktype);
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 42ef243..d3c69eb 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -430,7 +430,7 @@ 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);
+ inode = gfs2_inode_lookup(sb, DT_DIR, no_addr, 0, 0);
if (IS_ERR(inode)) {
fs_err(sdp, "can't read in %s inode: %ld
", name, PTR_ERR(inode));
return PTR_ERR(inode);
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index cf930cd..6fcae84 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -945,7 +945,7 @@ static void try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked, u64 skip
/* rgblk_search can return a block < goal, so we need to
keep it marching forward. */
no_addr = block + rgd->rd_data0;
- goal++;
+ goal = max(block + 1, goal + 1);
if (*last_unlinked != NO_BLOCK && no_addr <= *last_unlinked)
continue;
if (no_addr == skip)
@@ -971,7 +971,7 @@ static void try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked, u64 skip
found++;

/* Limit reclaim to sensible number of tasks */
- if (found > 2*NR_CPUS)
+ if (found > NR_CPUS)
return;
}

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 5b2cb81..b9f28e6 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1327,7 +1327,8 @@ static void gfs2_evict_inode(struct inode *inode)
if (inode->i_nlink || (sb->s_flags & MS_RDONLY))
goto out;

- error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
+ /* Must not read inode block until block type has been verified */
+ error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_SKIP, &gh);
if (unlikely(error)) {
gfs2_glock_dq_uninit(&ip->i_iopen_gh);
goto out;
@@ -1337,6 +1338,12 @@ static void gfs2_evict_inode(struct inode *inode)
if (error)
goto out_truncate;

+ if (test_bit(GIF_INVALID, &ip->i_flags)) {
+ error = gfs2_inode_refresh(ip);
+ if (error)
+ goto out_truncate;
+ }
+
ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
gfs2_glock_dq_wait(&ip->i_iopen_gh);
gfs2_holder_reinit(LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | GL_NOCACHE, &ip->i_iopen_gh);
--
1.7.4
 

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