Messages in this thread Patch in this message | | | Date | Fri, 28 Jan 2005 16:58:46 +0100 | From | Jan Blunck <> | Subject | [PATCH] d_drop should use per dentry lock |
| |
d_drop() must use the dentry->d_lock spinlock. In some cases __d_drop() was used without holding the dentry->d_lock spinlock, too. This could end in a race with __d_lookup().
Regards, Jan
Signed-off-by: Jan Blunck <j.blunck@tu-harburg.de>
fs/autofs4/root.c | 2 ++ fs/dcache.c | 3 +++ fs/namei.c | 14 +++++--------- fs/proc/base.c | 6 +++++- fs/sysfs/inode.c | 6 +++++- include/linux/dcache.h | 2 ++ 6 files changed, 22 insertions(+), 11 deletions(-)
Index: testing-um/include/linux/dcache.h =================================================================== --- testing-um.orig/include/linux/dcache.h 2005-01-28 15:06:27.000000000 +0100 +++ testing-um/include/linux/dcache.h 2005-01-28 15:58:15.000000000 +0100 @@ -186,7 +186,9 @@ static inline void d_drop(struct dentry *dentry) { spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); __d_drop(dentry); + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); } Index: testing-um/fs/namei.c =================================================================== --- testing-um.orig/fs/namei.c 2005-01-28 15:58:15.000000000 +0100 +++ testing-um/fs/namei.c 2005-01-28 15:58:15.000000000 +0100 @@ -1684,17 +1684,13 @@ void dentry_unhash(struct dentry *dentry) { dget(dentry); - spin_lock(&dcache_lock); - switch (atomic_read(&dentry->d_count)) { - default: - spin_unlock(&dcache_lock); + if (atomic_read(&dentry->d_count)) shrink_dcache_parent(dentry); - spin_lock(&dcache_lock); - if (atomic_read(&dentry->d_count) != 2) - break; - case 2: + spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); + if (atomic_read(&dentry->d_count) == 2) __d_drop(dentry); - } + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); } Index: testing-um/fs/sysfs/inode.c =================================================================== --- testing-um.orig/fs/sysfs/inode.c 2005-01-28 15:06:24.000000000 +0100 +++ testing-um/fs/sysfs/inode.c 2005-01-28 15:58:15.000000000 +0100 @@ -129,13 +129,17 @@ if (dentry) { spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); if (!(d_unhashed(dentry) && dentry->d_inode)) { dget_locked(dentry); __d_drop(dentry); + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); simple_unlink(parent->d_inode, dentry); - } else + } else { + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); + } } } Index: testing-um/fs/dcache.c =================================================================== --- testing-um.orig/fs/dcache.c 2005-01-28 15:53:19.000000000 +0100 +++ testing-um/fs/dcache.c 2005-01-28 16:52:49.609883016 +0100 @@ -340,13 +340,16 @@ tmp = head; while ((tmp = tmp->next) != head) { struct dentry *dentry = list_entry(tmp, struct dentry, d_alias); + spin_lock(&dentry->d_lock); if (!atomic_read(&dentry->d_count)) { __dget_locked(dentry); __d_drop(dentry); + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); dput(dentry); goto restart; } + spin_unlock(&dentry->d_lock); } spin_unlock(&dcache_lock); } Index: testing-um/fs/autofs4/root.c =================================================================== --- testing-um.orig/fs/autofs4/root.c 2005-01-28 15:53:22.000000000 +0100 +++ testing-um/fs/autofs4/root.c 2005-01-28 16:04:35.000000000 +0100 @@ -605,7 +605,9 @@ spin_unlock(&dcache_lock); return -ENOTEMPTY; } + spin_lock(&dentry->d_lock); __d_drop(dentry); + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); dput(ino->dentry); Index: testing-um/fs/proc/base.c =================================================================== --- testing-um.orig/fs/proc/base.c 2005-01-28 15:53:38.000000000 +0100 +++ testing-um/fs/proc/base.c 2005-01-28 16:29:14.000000000 +0100 @@ -1468,11 +1468,15 @@ if (proc_dentry != NULL) { spin_lock(&dcache_lock); + spin_lock(&proc_dentry->d_lock); if (!d_unhashed(proc_dentry)) { dget_locked(proc_dentry); __d_drop(proc_dentry); - } else + spin_unlock(&proc_dentry->d_lock); + } else { + spin_unlock(&proc_dentry->d_lock); proc_dentry = NULL; + } spin_unlock(&dcache_lock); } return proc_dentry; | |