[patch 3/3] dentry->d_count fixes

From: Maneesh Soni (maneesh@in.ibm.com)
Date: Thu Jun 19 2003 - 08:11:13 EST

- hpfs_unlink() can race with lockless d_lookup(), as we can have situations
  where d_lookup() has successfully looked-up a dentry and at the sametime
  hpfs_unlink()--->d_drop() has dropped it. Taking the per dentry lock
  before checking the d_count in hpfs_unlink() solves this race condition.

 fs/hpfs/namei.c | 3 +++
 1 files changed, 3 insertions(+)

diff -puN fs/hpfs/namei.c~hpfs-d_count-fix fs/hpfs/namei.c
--- linux-2.5.72-mm2/fs/hpfs/namei.c~hpfs-d_count-fix 2003-06-19 17:46:05.000000000 +0530
+++ linux-2.5.72-mm2-maneesh/fs/hpfs/namei.c 2003-06-19 17:46:19.000000000 +0530
@@ -372,12 +372,15 @@ again:
                 if (rep)
                         goto ret;
                 d_drop(dentry);
+ spin_lock(&dentry->d_lock);
                 if (atomic_read(&dentry->d_count) > 1 ||
                     permission(inode, MAY_WRITE) ||
                     get_write_access(inode)) {
+ spin_unlock(&dentry->d_lock);
                         d_rehash(dentry);
                         goto ret;
                 }
+ spin_unlock(&dentry->d_lock);
                 /*printk("HPFS: truncating file before delete.\n");*/
                 newattrs.ia_size = 0;
                 newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;

_ 

-- 
Maneesh Soni
IBM Linux Technology Center, 
IBM India Software Lab, Bangalore.
Phone: +91-80-5044999 email: maneesh@in.ibm.com
http://lse.sourceforge.net/
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This archive was generated by hypermail 2b29 : Mon Jun 23 2003 - 22:00:29 EST