| Message ID | 20170116064220.23720-3-zren@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 01/16/2017 02:42 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(). > > Changes since v1: > 1. Let ocfs2_is_locked_by_me() just return true/false to indicate if the > process gets the cluster lock - suggested by: Joseph Qi <jiangqi903@gmail.com> > and Junxiao Bi <junxiao.bi@oracle.com>. > > 2. Change "struct ocfs2_holder" to a more meaningful name "ocfs2_lock_holder", > suggested by: Junxiao Bi <junxiao.bi@oracle.com>. > > 3. Add debugging output at ocfs2_setattr() and ocfs2_permission() to > catch exceptional cases, suggested by: Junxiao Bi <junxiao.bi@oracle.com>. > > Signed-off-by: Eric Ren <zren@suse.com> > --- > fs/ocfs2/acl.c | 39 +++++++++++++++++++++++++---- > fs/ocfs2/file.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++-------- > 2 files changed, 100 insertions(+), 15 deletions(-) > > diff --git a/fs/ocfs2/acl.c b/fs/ocfs2/acl.c > index bed1fcb..3e47262 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_lock_holder oh; > + struct ocfs2_lock_res *lockres; > + > + lockres = &OCFS2_I(inode)->ip_inode_lockres; > + has_locked = ocfs2_is_locked_by_me(lockres); > + 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); > + Same code pattern showed here and *get_acl, can it be abstracted to one function? The same issue for *setattr and *permission. Sorry for not mention that in last review. Thanks, Junxiao. > 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_lock_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); > + 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..b620c25 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_lock_holder oh; > + struct ocfs2_lock_res *lockres; > > trace_ocfs2_setattr(inode, dentry, > (unsigned long long)OCFS2_I(inode)->ip_blkno, > @@ -1173,13 +1176,41 @@ 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); > + if (had_lock) { > + arg_flags = OCFS2_META_LOCK_GETBH; > + > + /* > + * As far as we know, ocfs2_setattr() could only be the first > + * VFS entry point in the call chain of recursive cluster > + * locking issue. > + * > + * For instance: > + * chmod_common() > + * notify_change() > + * ocfs2_setattr() > + * posix_acl_chmod() > + * ocfs2_iop_get_acl() > + * > + * But, we're not 100% sure if it's always true, because the > + * ordering of the VFS entry points in the call chain is out > + * of our control. So, we'd better dump the stack here to > + * catch the other cases of recursive locking. > + */ > + mlog(ML_ERROR, "Another case of recursive locking:\n"); > + dump_stack(); > + } > + 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 +1291,8 @@ 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 +1310,10 @@ 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 +1355,42 @@ int ocfs2_getattr(struct vfsmount *mnt, > int ocfs2_permission(struct inode *inode, int mask) > { > int ret; > + int has_locked; > + struct ocfs2_lock_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); > + 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); > + } else { > + /* See comments in ocfs2_setattr() for details. > + * The call chain of this case could be: > + * do_sys_open() > + * may_open() > + * inode_permission() > + * ocfs2_permission() > + * ocfs2_iop_get_acl() > + */ > + mlog(ML_ERROR, "Another case of recursive locking:\n"); > + dump_stack(); > } > > 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; > } >
Hi! On 01/16/2017 02:58 PM, Junxiao Bi wrote: > On 01/16/2017 02:42 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(). >> >> Changes since v1: >> 1. Let ocfs2_is_locked_by_me() just return true/false to indicate if the >> process gets the cluster lock - suggested by: Joseph Qi <jiangqi903@gmail.com> >> and Junxiao Bi <junxiao.bi@oracle.com>. >> >> 2. Change "struct ocfs2_holder" to a more meaningful name "ocfs2_lock_holder", >> suggested by: Junxiao Bi <junxiao.bi@oracle.com>. >> >> 3. Add debugging output at ocfs2_setattr() and ocfs2_permission() to >> catch exceptional cases, suggested by: Junxiao Bi <junxiao.bi@oracle.com>. >> >> Signed-off-by: Eric Ren <zren@suse.com> >> --- >> fs/ocfs2/acl.c | 39 +++++++++++++++++++++++++---- >> fs/ocfs2/file.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++-------- >> 2 files changed, 100 insertions(+), 15 deletions(-) >> >> diff --git a/fs/ocfs2/acl.c b/fs/ocfs2/acl.c >> index bed1fcb..3e47262 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_lock_holder oh; >> + struct ocfs2_lock_res *lockres; >> + >> + lockres = &OCFS2_I(inode)->ip_inode_lockres; >> + has_locked = ocfs2_is_locked_by_me(lockres); >> + 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); >> + > Same code pattern showed here and *get_acl, can it be abstracted to one > function? > The same issue for *setattr and *permission. Sorry for not mention that > in last review. Good idea! I will do it in the next version;-) Thanks, Eric > > Thanks, > Junxiao. >> 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_lock_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); >> + 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..b620c25 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_lock_holder oh; >> + struct ocfs2_lock_res *lockres; >> >> trace_ocfs2_setattr(inode, dentry, >> (unsigned long long)OCFS2_I(inode)->ip_blkno, >> @@ -1173,13 +1176,41 @@ 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); >> + if (had_lock) { >> + arg_flags = OCFS2_META_LOCK_GETBH; >> + >> + /* >> + * As far as we know, ocfs2_setattr() could only be the first >> + * VFS entry point in the call chain of recursive cluster >> + * locking issue. >> + * >> + * For instance: >> + * chmod_common() >> + * notify_change() >> + * ocfs2_setattr() >> + * posix_acl_chmod() >> + * ocfs2_iop_get_acl() >> + * >> + * But, we're not 100% sure if it's always true, because the >> + * ordering of the VFS entry points in the call chain is out >> + * of our control. So, we'd better dump the stack here to >> + * catch the other cases of recursive locking. >> + */ >> + mlog(ML_ERROR, "Another case of recursive locking:\n"); >> + dump_stack(); >> + } >> + 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 +1291,8 @@ 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 +1310,10 @@ 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 +1355,42 @@ int ocfs2_getattr(struct vfsmount *mnt, >> int ocfs2_permission(struct inode *inode, int mask) >> { >> int ret; >> + int has_locked; >> + struct ocfs2_lock_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); >> + 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); >> + } else { >> + /* See comments in ocfs2_setattr() for details. >> + * The call chain of this case could be: >> + * do_sys_open() >> + * may_open() >> + * inode_permission() >> + * ocfs2_permission() >> + * ocfs2_iop_get_acl() >> + */ >> + mlog(ML_ERROR, "Another case of recursive locking:\n"); >> + dump_stack(); >> } >> >> 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; >> } >> >
diff --git a/fs/ocfs2/acl.c b/fs/ocfs2/acl.c index bed1fcb..3e47262 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_lock_holder oh; + struct ocfs2_lock_res *lockres; + + lockres = &OCFS2_I(inode)->ip_inode_lockres; + has_locked = ocfs2_is_locked_by_me(lockres); + 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_lock_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); + 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..b620c25 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_lock_holder oh; + struct ocfs2_lock_res *lockres; trace_ocfs2_setattr(inode, dentry, (unsigned long long)OCFS2_I(inode)->ip_blkno, @@ -1173,13 +1176,41 @@ 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); + if (had_lock) { + arg_flags = OCFS2_META_LOCK_GETBH; + + /* + * As far as we know, ocfs2_setattr() could only be the first + * VFS entry point in the call chain of recursive cluster + * locking issue. + * + * For instance: + * chmod_common() + * notify_change() + * ocfs2_setattr() + * posix_acl_chmod() + * ocfs2_iop_get_acl() + * + * But, we're not 100% sure if it's always true, because the + * ordering of the VFS entry points in the call chain is out + * of our control. So, we'd better dump the stack here to + * catch the other cases of recursive locking. + */ + mlog(ML_ERROR, "Another case of recursive locking:\n"); + dump_stack(); + } + 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 +1291,8 @@ 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 +1310,10 @@ 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 +1355,42 @@ int ocfs2_getattr(struct vfsmount *mnt, int ocfs2_permission(struct inode *inode, int mask) { int ret; + int has_locked; + struct ocfs2_lock_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); + 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); + } else { + /* See comments in ocfs2_setattr() for details. + * The call chain of this case could be: + * do_sys_open() + * may_open() + * inode_permission() + * ocfs2_permission() + * ocfs2_iop_get_acl() + */ + mlog(ML_ERROR, "Another case of recursive locking:\n"); + dump_stack(); } 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; }
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(). Changes since v1: 1. Let ocfs2_is_locked_by_me() just return true/false to indicate if the process gets the cluster lock - suggested by: Joseph Qi <jiangqi903@gmail.com> and Junxiao Bi <junxiao.bi@oracle.com>. 2. Change "struct ocfs2_holder" to a more meaningful name "ocfs2_lock_holder", suggested by: Junxiao Bi <junxiao.bi@oracle.com>. 3. Add debugging output at ocfs2_setattr() and ocfs2_permission() to catch exceptional cases, suggested by: Junxiao Bi <junxiao.bi@oracle.com>. Signed-off-by: Eric Ren <zren@suse.com> --- fs/ocfs2/acl.c | 39 +++++++++++++++++++++++++---- fs/ocfs2/file.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 100 insertions(+), 15 deletions(-)