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ocfs2: cache the mount context for dentry lock callbacks

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ocfs2_drop_dentry_lock() drops the inode reference before releasing the
DENTRY lock.  This lets inode eviction release the local inode and open
locks before a remote unlink can proceed past the DENTRY lock.

A DLM callback can still arrive before the DENTRY lock has been dropped.
ocfs2_get_dentry_osb() obtains the mount context through dl_inode->i_sb,
which can access a freed inode when the downconvert thread drops the
last inode reference in its post-unlock callback:

  Downconvert thread                     DLM callback thread
  ------------------                     -------------------
  ocfs2_process_blocked_lock()
    ocfs2_dentry_post_unlock()
      ocfs2_dentry_lock_put()
        ocfs2_drop_dentry_lock()
          iput(dl->dl_inode)
          [inode reclaimed after RCU]
                                         ocfs2_blocking_ast()
                                           ocfs2_get_dentry_osb()
                                             dl->dl_inode->i_sb
          ocfs2_simple_drop_lockres()

Store the mount context in the DENTRY lock resource's l_priv field and use
the default mount-context lookup.  Recover the containing dentry lock with
container_of(), as already done for refcount locks, and remove
ocfs2_get_dentry_osb().  ocfs2_dismount_volume() shuts down the DLM before
freeing the mount context, so callbacks can use it without accessing the
inode.  Preserve the existing iput-before-unlock order to avoid delaying
local inode and open lock release until after the DENTRY lock is released.

Link: https://lore.kernel.org/pm-ocfs2-objects-candidate-0012-v9-eeb9084fb29577971229@gmail.com
Fixes: 8ed6b23709 ("ocfs2: revert iput deferring code in ocfs2_drop_dentry_lock")
Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Assisted-by: LLM
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>
Cc: <jjzuming@gmail.com>
Cc: <stable@vger.kernel.org>
This commit is contained in:
Cen Zhang 2026-10-20 22:25:53 +08:00 committed by Andrew Morton
parent a25c02af29
commit 5b4696e0bf
2 changed files with 6 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
fs/ocfs2/dcache.h
View File

@ -17,9 +17,8 @@ struct ocfs2_dentry_lock {
u64 dl_parent_blkno;
/*
* The ocfs2_dentry_lock keeps an inode reference until
* dl_lockres has been destroyed. This is usually done in
* ->d_iput() anyway, so there should be minimal impact.
* The inode reference is dropped before dl_lockres is unlocked.
* Callbacks must not use it to find the mount context during teardown.
*/
struct inode *dl_inode;
struct ocfs2_lock_res dl_lockres;

16
fs/ocfs2/dlmglue.c
View File

@ -58,7 +58,6 @@ struct ocfs2_mask_waiter {
#endif
};
static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres);
static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres);
static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres);
static struct ocfs2_super *ocfs2_get_qinfo_osb(struct ocfs2_lock_res *lockres);
@ -258,7 +257,6 @@ static const struct ocfs2_lock_res_ops ocfs2_orphan_scan_lops = {
};
static const struct ocfs2_lock_res_ops ocfs2_dentry_lops = {
.get_osb = ocfs2_get_dentry_osb,
.post_unlock = ocfs2_dentry_post_unlock,
.downconvert_worker = ocfs2_dentry_convert_worker,
.flags = 0,
@ -309,7 +307,7 @@ static inline struct ocfs2_dentry_lock *ocfs2_lock_res_dl(struct ocfs2_lock_res
{
BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_DENTRY);
return (struct ocfs2_dentry_lock *)lockres->l_priv;
return container_of(lockres, struct ocfs2_dentry_lock, dl_lockres);
}
static inline struct ocfs2_mem_dqinfo *ocfs2_lock_res_qinfo(struct ocfs2_lock_res *lockres)
@ -610,13 +608,6 @@ static __u64 ocfs2_get_dentry_lock_ino(struct ocfs2_lock_res *lockres)
return be64_to_cpu(inode_blkno_be);
}
static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres)
{
struct ocfs2_dentry_lock *dl = lockres->l_priv;
return OCFS2_SB(dl->dl_inode->i_sb);
}
void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
u64 parent, struct inode *inode)
{
@ -624,6 +615,7 @@ void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
u64 inode_blkno = OCFS2_I(inode)->ip_blkno;
__be64 inode_blkno_be = cpu_to_be64(inode_blkno);
struct ocfs2_lock_res *lockres = &dl->dl_lockres;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
ocfs2_lock_res_init_once(lockres);
@ -652,9 +644,9 @@ void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
memcpy(&lockres->l_name[OCFS2_DENTRY_LOCK_INO_START], &inode_blkno_be,
sizeof(__be64));
ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
ocfs2_lock_res_init_common(osb, lockres,
OCFS2_LOCK_TYPE_DENTRY, &ocfs2_dentry_lops,
dl);
osb);
}
static void ocfs2_super_lock_res_init(struct ocfs2_lock_res *res,