Junxiao Bi
2017-Jan-13 04:22 UTC
[Ocfs2-devel] [PATCH 2/2] ocfs2: fix deadlocks when taking inode lock at vfs entry points
On 01/05/2017 11:31 PM, Eric Ren wrote:> Commit 743b5f1434f5 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()") > results in a deadlock, as the author "Tariq Saeed" realized shortly > after the patch was merged. The discussion happened here > (https://oss.oracle.com/pipermail/ocfs2-devel/2015-September/011085.html). > > The reason why taking cluster inode lock at vfs entry points opens up > a self deadlock window, is explained in the previous patch of this > series. > > So far, we have seen two different code paths that have this issue. > 1. do_sys_open > may_open > inode_permission > ocfs2_permission > ocfs2_inode_lock() <=== take PR > generic_permission > get_acl > ocfs2_iop_get_acl > ocfs2_inode_lock() <=== take PR > 2. fchmod|fchmodat > chmod_common > notify_change > ocfs2_setattr <=== take EX > posix_acl_chmod > get_acl > ocfs2_iop_get_acl <=== take PR > ocfs2_iop_set_acl <=== take EX > > Fixes them by adding the tracking logic (in the previous patch) for > these funcs above, ocfs2_permission(), ocfs2_iop_[set|get]_acl(), > ocfs2_setattr(). > > Signed-off-by: Eric Ren <zren at suse.com> > --- > fs/ocfs2/acl.c | 39 ++++++++++++++++++++++++++++++++++----- > fs/ocfs2/file.c | 44 ++++++++++++++++++++++++++++++++++---------- > 2 files changed, 68 insertions(+), 15 deletions(-) > > diff --git a/fs/ocfs2/acl.c b/fs/ocfs2/acl.c > index bed1fcb..c539890 100644 > --- a/fs/ocfs2/acl.c > +++ b/fs/ocfs2/acl.c > @@ -284,16 +284,31 @@ int ocfs2_iop_set_acl(struct inode *inode, struct posix_acl *acl, int type) > { > struct buffer_head *bh = NULL; > int status = 0; > - > - status = ocfs2_inode_lock(inode, &bh, 1); > + int arg_flags = 0, has_locked; > + struct ocfs2_holder oh; > + struct ocfs2_lock_res *lockres; > + > + lockres = &OCFS2_I(inode)->ip_inode_lockres; > + has_locked = (ocfs2_is_locked_by_me(lockres) != NULL); > + if (has_locked) > + arg_flags = OCFS2_META_LOCK_GETBH; > + status = ocfs2_inode_lock_full(inode, &bh, 1, arg_flags); > if (status < 0) { > if (status != -ENOENT) > mlog_errno(status); > return status; > } > + if (!has_locked) > + ocfs2_add_holder(lockres, &oh); > + > status = ocfs2_set_acl(NULL, inode, bh, type, acl, NULL, NULL); > - ocfs2_inode_unlock(inode, 1); > + > + if (!has_locked) { > + ocfs2_remove_holder(lockres, &oh); > + ocfs2_inode_unlock(inode, 1); > + } > brelse(bh); > + > return status; > } > > @@ -303,21 +318,35 @@ struct posix_acl *ocfs2_iop_get_acl(struct inode *inode, int type) > struct buffer_head *di_bh = NULL; > struct posix_acl *acl; > int ret; > + int arg_flags = 0, has_locked; > + struct ocfs2_holder oh; > + struct ocfs2_lock_res *lockres; > > osb = OCFS2_SB(inode->i_sb); > if (!(osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL)) > return NULL; > - ret = ocfs2_inode_lock(inode, &di_bh, 0); > + > + lockres = &OCFS2_I(inode)->ip_inode_lockres; > + has_locked = (ocfs2_is_locked_by_me(lockres) != NULL); > + if (has_locked) > + arg_flags = OCFS2_META_LOCK_GETBH; > + ret = ocfs2_inode_lock_full(inode, &di_bh, 0, arg_flags); > if (ret < 0) { > if (ret != -ENOENT) > mlog_errno(ret); > return ERR_PTR(ret); > } > + if (!has_locked) > + ocfs2_add_holder(lockres, &oh); > > acl = ocfs2_get_acl_nolock(inode, type, di_bh); > > - ocfs2_inode_unlock(inode, 0); > + if (!has_locked) { > + ocfs2_remove_holder(lockres, &oh); > + ocfs2_inode_unlock(inode, 0); > + } > brelse(di_bh); > + > return acl; > } > > diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c > index c488965..62be75d 100644 > --- a/fs/ocfs2/file.c > +++ b/fs/ocfs2/file.c > @@ -1138,6 +1138,9 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) > handle_t *handle = NULL; > struct dquot *transfer_to[MAXQUOTAS] = { }; > int qtype; > + int arg_flags = 0, had_lock; > + struct ocfs2_holder oh; > + struct ocfs2_lock_res *lockres; > > trace_ocfs2_setattr(inode, dentry, > (unsigned long long)OCFS2_I(inode)->ip_blkno, > @@ -1173,13 +1176,20 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) > } > } > > - status = ocfs2_inode_lock(inode, &bh, 1); > + lockres = &OCFS2_I(inode)->ip_inode_lockres; > + had_lock = (ocfs2_is_locked_by_me(lockres) != NULL);If had_lock==true, it is a bug? I think we should BUG_ON for it, that can help us catch bug at the first time.> + if (had_lock) > + arg_flags = OCFS2_META_LOCK_GETBH; > + status = ocfs2_inode_lock_full(inode, &bh, 1, arg_flags); > if (status < 0) { > if (status != -ENOENT) > mlog_errno(status); > goto bail_unlock_rw; > } > - inode_locked = 1; > + if (!had_lock) { > + ocfs2_add_holder(lockres, &oh); > + inode_locked = 1; > + } > > if (size_change) { > status = inode_newsize_ok(inode, attr->ia_size); > @@ -1260,7 +1270,8 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) > bail_commit: > ocfs2_commit_trans(osb, handle); > bail_unlock: > - if (status) { > + if (status && inode_locked) { > + ocfs2_remove_holder(lockres, &oh); > ocfs2_inode_unlock(inode, 1); > inode_locked = 0; > } > @@ -1278,8 +1289,10 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) > if (status < 0) > mlog_errno(status); > } > - if (inode_locked) > + if (inode_locked) { > + ocfs2_remove_holder(lockres, &oh); > ocfs2_inode_unlock(inode, 1); > + } > > brelse(bh); > return status; > @@ -1321,20 +1334,31 @@ int ocfs2_getattr(struct vfsmount *mnt, > int ocfs2_permission(struct inode *inode, int mask) > { > int ret; > + int has_locked; > + struct ocfs2_holder oh; > + struct ocfs2_lock_res *lockres; > > if (mask & MAY_NOT_BLOCK) > return -ECHILD; > > - ret = ocfs2_inode_lock(inode, NULL, 0); > - if (ret) { > - if (ret != -ENOENT) > - mlog_errno(ret); > - goto out; > + lockres = &OCFS2_I(inode)->ip_inode_lockres; > + has_locked = (ocfs2_is_locked_by_me(lockres) != NULL);The same thing as ocfs2_setattr. Thanks, Junxiao.> + if (!has_locked) { > + ret = ocfs2_inode_lock(inode, NULL, 0); > + if (ret) { > + if (ret != -ENOENT) > + mlog_errno(ret); > + goto out; > + } > + ocfs2_add_holder(lockres, &oh); > } > > ret = generic_permission(inode, mask); > > - ocfs2_inode_unlock(inode, 0); > + if (!has_locked) { > + ocfs2_remove_holder(lockres, &oh); > + ocfs2_inode_unlock(inode, 0); > + } > out: > return ret; > } >
Eric Ren
2017-Jan-13 06:19 UTC
[Ocfs2-devel] [PATCH 2/2] ocfs2: fix deadlocks when taking inode lock at vfs entry points
Hi! On 01/13/2017 12:22 PM, Junxiao Bi wrote:> On 01/05/2017 11:31 PM, Eric Ren wrote: >> Commit 743b5f1434f5 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()") >> results in a deadlock, as the author "Tariq Saeed" realized shortly >> after the patch was merged. The discussion happened here >> (https://oss.oracle.com/pipermail/ocfs2-devel/2015-September/011085.html). >> >> The reason why taking cluster inode lock at vfs entry points opens up >> a self deadlock window, is explained in the previous patch of this >> series. >> >> So far, we have seen two different code paths that have this issue. >> 1. do_sys_open >> may_open >> inode_permission >> ocfs2_permission >> ocfs2_inode_lock() <=== take PR >> generic_permission >> get_acl >> ocfs2_iop_get_acl >> ocfs2_inode_lock() <=== take PR >> 2. fchmod|fchmodat >> chmod_common >> notify_change >> ocfs2_setattr <=== take EX >> posix_acl_chmod >> get_acl >> ocfs2_iop_get_acl <=== take PR >> ocfs2_iop_set_acl <=== take EX >> >> Fixes them by adding the tracking logic (in the previous patch) for >> these funcs above, ocfs2_permission(), ocfs2_iop_[set|get]_acl(), >> ocfs2_setattr(). >> >> Signed-off-by: Eric Ren <zren at suse.com> >> --- >> fs/ocfs2/acl.c | 39 ++++++++++++++++++++++++++++++++++----- >> fs/ocfs2/file.c | 44 ++++++++++++++++++++++++++++++++++---------- >> 2 files changed, 68 insertions(+), 15 deletions(-) >> >> diff --git a/fs/ocfs2/acl.c b/fs/ocfs2/acl.c >> index bed1fcb..c539890 100644 >> --- a/fs/ocfs2/acl.c >> +++ b/fs/ocfs2/acl.c >> @@ -284,16 +284,31 @@ int ocfs2_iop_set_acl(struct inode *inode, struct posix_acl *acl, int type) >> { >> struct buffer_head *bh = NULL; >> int status = 0; >> - >> - status = ocfs2_inode_lock(inode, &bh, 1); >> + int arg_flags = 0, has_locked; >> + struct ocfs2_holder oh; >> + struct ocfs2_lock_res *lockres; >> + >> + lockres = &OCFS2_I(inode)->ip_inode_lockres; >> + has_locked = (ocfs2_is_locked_by_me(lockres) != NULL); >> + if (has_locked) >> + arg_flags = OCFS2_META_LOCK_GETBH; >> + status = ocfs2_inode_lock_full(inode, &bh, 1, arg_flags); >> if (status < 0) { >> if (status != -ENOENT) >> mlog_errno(status); >> return status; >> } >> + if (!has_locked) >> + ocfs2_add_holder(lockres, &oh); >> + >> status = ocfs2_set_acl(NULL, inode, bh, type, acl, NULL, NULL); >> - ocfs2_inode_unlock(inode, 1); >> + >> + if (!has_locked) { >> + ocfs2_remove_holder(lockres, &oh); >> + ocfs2_inode_unlock(inode, 1); >> + } >> brelse(bh); >> + >> return status; >> } >> >> @@ -303,21 +318,35 @@ struct posix_acl *ocfs2_iop_get_acl(struct inode *inode, int type) >> struct buffer_head *di_bh = NULL; >> struct posix_acl *acl; >> int ret; >> + int arg_flags = 0, has_locked; >> + struct ocfs2_holder oh; >> + struct ocfs2_lock_res *lockres; >> >> osb = OCFS2_SB(inode->i_sb); >> if (!(osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL)) >> return NULL; >> - ret = ocfs2_inode_lock(inode, &di_bh, 0); >> + >> + lockres = &OCFS2_I(inode)->ip_inode_lockres; >> + has_locked = (ocfs2_is_locked_by_me(lockres) != NULL); >> + if (has_locked) >> + arg_flags = OCFS2_META_LOCK_GETBH; >> + ret = ocfs2_inode_lock_full(inode, &di_bh, 0, arg_flags); >> if (ret < 0) { >> if (ret != -ENOENT) >> mlog_errno(ret); >> return ERR_PTR(ret); >> } >> + if (!has_locked) >> + ocfs2_add_holder(lockres, &oh); >> >> acl = ocfs2_get_acl_nolock(inode, type, di_bh); >> >> - ocfs2_inode_unlock(inode, 0); >> + if (!has_locked) { >> + ocfs2_remove_holder(lockres, &oh); >> + ocfs2_inode_unlock(inode, 0); >> + } >> brelse(di_bh); >> + >> return acl; >> } >> >> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c >> index c488965..62be75d 100644 >> --- a/fs/ocfs2/file.c >> +++ b/fs/ocfs2/file.c >> @@ -1138,6 +1138,9 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) >> handle_t *handle = NULL; >> struct dquot *transfer_to[MAXQUOTAS] = { }; >> int qtype; >> + int arg_flags = 0, had_lock; >> + struct ocfs2_holder oh; >> + struct ocfs2_lock_res *lockres; >> >> trace_ocfs2_setattr(inode, dentry, >> (unsigned long long)OCFS2_I(inode)->ip_blkno, >> @@ -1173,13 +1176,20 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) >> } >> } >> >> - status = ocfs2_inode_lock(inode, &bh, 1); >> + lockres = &OCFS2_I(inode)->ip_inode_lockres; >> + had_lock = (ocfs2_is_locked_by_me(lockres) != NULL); > If had_lock==true, it is a bug? I think we should BUG_ON for it, that > can help us catch bug at the first time.Good idea! But I'm not sure if "ocfs2_setattr" is always the first one who takes the cluster lock. It's harder for me to name all the possible paths;-/> > >> + if (had_lock) >> + arg_flags = OCFS2_META_LOCK_GETBH; >> + status = ocfs2_inode_lock_full(inode, &bh, 1, arg_flags); >> if (status < 0) { >> if (status != -ENOENT) >> mlog_errno(status); >> goto bail_unlock_rw; >> } >> - inode_locked = 1; >> + if (!had_lock) { >> + ocfs2_add_holder(lockres, &oh); >> + inode_locked = 1; >> + } >> >> if (size_change) { >> status = inode_newsize_ok(inode, attr->ia_size); >> @@ -1260,7 +1270,8 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) >> bail_commit: >> ocfs2_commit_trans(osb, handle); >> bail_unlock: >> - if (status) { >> + if (status && inode_locked) { >> + ocfs2_remove_holder(lockres, &oh); >> ocfs2_inode_unlock(inode, 1); >> inode_locked = 0; >> } >> @@ -1278,8 +1289,10 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) >> if (status < 0) >> mlog_errno(status); >> } >> - if (inode_locked) >> + if (inode_locked) { >> + ocfs2_remove_holder(lockres, &oh); >> ocfs2_inode_unlock(inode, 1); >> + } >> >> brelse(bh); >> return status; >> @@ -1321,20 +1334,31 @@ int ocfs2_getattr(struct vfsmount *mnt, >> int ocfs2_permission(struct inode *inode, int mask) >> { >> int ret; >> + int has_locked; >> + struct ocfs2_holder oh; >> + struct ocfs2_lock_res *lockres; >> >> if (mask & MAY_NOT_BLOCK) >> return -ECHILD; >> >> - ret = ocfs2_inode_lock(inode, NULL, 0); >> - if (ret) { >> - if (ret != -ENOENT) >> - mlog_errno(ret); >> - goto out; >> + lockres = &OCFS2_I(inode)->ip_inode_lockres; >> + has_locked = (ocfs2_is_locked_by_me(lockres) != NULL); > The same thing as ocfs2_setattr.OK. I will think over your suggestions! Thanks, Eric> > Thanks, > Junxiao. >> + if (!has_locked) { >> + ret = ocfs2_inode_lock(inode, NULL, 0); >> + if (ret) { >> + if (ret != -ENOENT) >> + mlog_errno(ret); >> + goto out; >> + } >> + ocfs2_add_holder(lockres, &oh); >> } >> >> ret = generic_permission(inode, mask); >> >> - ocfs2_inode_unlock(inode, 0); >> + if (!has_locked) { >> + ocfs2_remove_holder(lockres, &oh); >> + ocfs2_inode_unlock(inode, 0); >> + } >> out: >> return ret; >> } >> >