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Go Back   Linux Archive > Redhat > Cluster Development

 
 
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Old 05-17-2010, 12:40 PM
Steven Whitehouse
 
Default GFS2: glock livelock

From: Bob Peterson <rpeterso@redhat.com>

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>
---
fs/gfs2/dir.c | 2 +-
fs/gfs2/export.c | 2 +-
fs/gfs2/glock.c | 3 +
fs/gfs2/inode.c | 101 +++++++++++++++++++++++++++++++++++++++++++++----
fs/gfs2/inode.h | 5 +-
fs/gfs2/ops_fstype.c | 2 +-
fs/gfs2/rgrp.c | 58 +++++++++++++++++++++-------
7 files changed, 144 insertions(+), 29 deletions(-)

diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index 25fddc1..8295c5b 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 d15876e..d81bc7e 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 454d4b4..ddcdbf4 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 b1bf269..51d8061 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 c341aaf..e161461 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 c1309ed..dc35f34 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
", name, PTR_ERR(inode));
return PTR_ERR(inode);
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 503b842..3739155 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:
--
1.6.2.5
 

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