From: Maneesh Soni <maneesh@in.ibm.com>
This patch changes the way DCACHE_REFERENCED flag is used. It
got messed up in dcache_rcu iterations. I hope this will be ok now.
The flag was meant to be advisory flag which is used while
prune_dcache() so as not to free dentries which have recently
entered d_lru list. At first pass in prune_dcache the dentries
marked DCACHE_REFERENCED are left with the flag reset. and they
are freed in the next pass.
So, now we mark the dentry as DCACHE_REFERENCED when it is first
entering the d_lru list in dput() and resetthe flag in prune_dcache().
If the flag remains reset in the next call to prune_dcache(), the
dentry is then freed.
Also I don't think any file system have to use this flag as it is taken
care by the dcache layer. The patch removes such code from a few of file
systems. Moreover these filesystems were anyway doing worng thing as they
were changing the flag out of dcache_lock.
Changes:
o dput() marks dentry DCACHE_REFERENCED when it is added to the dentry_unused
list
o no need to set the flag in dget, dget_locked, d_lookup as these guys anyway
increments the ref count.
o check the ref count in prune_dcache and use DCACHE_REFERENCED flag just for
two stage aging.
o remove code for setting DACACHE_REFERENCED from reiserfs, fat, xfs and
exportfs.
fs/dcache.c | 20 ++++++++------------
fs/exportfs/expfs.c | 3 ---
fs/fat/inode.c | 1 -
fs/reiserfs/inode.c | 1 -
fs/xfs/linux/xfs_super.c | 1 -
include/linux/dcache.h | 1 -
6 files changed, 8 insertions(+), 19 deletions(-)
diff -puN fs/dcache.c~DCACHE_REFERENCED-fixes fs/dcache.c
--- 25/fs/dcache.c~DCACHE_REFERENCED-fixes 2003-04-14 12:20:24.000000000 -0700
+++ 25-akpm/fs/dcache.c 2003-04-14 12:20:24.000000000 -0700
@@ -155,12 +155,11 @@ repeat:
if (d_unhashed(dentry))
goto kill_it;
if (list_empty(&dentry->d_lru)) {
- dentry->d_vfs_flags &= ~DCACHE_REFERENCED;
+ dentry->d_vfs_flags |= DCACHE_REFERENCED;
list_add(&dentry->d_lru, &dentry_unused);
dentry_stat.nr_unused++;
}
spin_unlock(&dentry->d_lock);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
spin_unlock(&dcache_lock);
return;
@@ -250,7 +249,6 @@ int d_invalidate(struct dentry * dentry)
static inline struct dentry * __dget_locked(struct dentry *dentry)
{
atomic_inc(&dentry->d_count);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
if (atomic_read(&dentry->d_count) == 1) {
dentry_stat.nr_unused--;
list_del_init(&dentry->d_lru);
@@ -379,17 +377,16 @@ static void prune_dcache(int count)
dentry = list_entry(tmp, struct dentry, d_lru);
spin_lock(&dentry->d_lock);
+ /* leave inuse dentries */
+ if (atomic_read(&dentry->d_count)) {
+ spin_unlock(&dentry->d_lock);
+ continue;
+ }
/* If the dentry was recently referenced, don't free it. */
if (dentry->d_vfs_flags & DCACHE_REFERENCED) {
dentry->d_vfs_flags &= ~DCACHE_REFERENCED;
-
- /* don't add non zero d_count dentries
- * back to d_lru list
- */
- if (!atomic_read(&dentry->d_count)) {
- list_add(&dentry->d_lru, &dentry_unused);
- dentry_stat.nr_unused++;
- }
+ list_add(&dentry->d_lru, &dentry_unused);
+ dentry_stat.nr_unused++;
spin_unlock(&dentry->d_lock);
continue;
}
@@ -1027,7 +1024,6 @@ struct dentry * __d_lookup(struct dentry
if (likely(move_count == dentry->d_move_count)) {
if (!d_unhashed(dentry)) {
atomic_inc(&dentry->d_count);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
found = dentry;
}
}
diff -puN fs/exportfs/expfs.c~DCACHE_REFERENCED-fixes fs/exportfs/expfs.c
--- 25/fs/exportfs/expfs.c~DCACHE_REFERENCED-fixes 2003-04-14 12:20:24.000000000 -0700
+++ 25-akpm/fs/exportfs/expfs.c 2003-04-14 12:20:24.000000000 -0700
@@ -91,7 +91,6 @@ find_exported_dentry(struct super_block
if (dentry != result &&
acceptable(context, dentry)) {
dput(result);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
return dentry;
}
spin_lock(&dcache_lock);
@@ -271,7 +270,6 @@ find_exported_dentry(struct super_block
if (dentry != result &&
acceptable(context, dentry)) {
dput(result);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
return dentry;
}
spin_lock(&dcache_lock);
@@ -434,7 +432,6 @@ static struct dentry *export_iget(struct
iput(inode);
return ERR_PTR(-ENOMEM);
}
- result->d_vfs_flags |= DCACHE_REFERENCED;
return result;
}
diff -puN fs/fat/inode.c~DCACHE_REFERENCED-fixes fs/fat/inode.c
--- 25/fs/fat/inode.c~DCACHE_REFERENCED-fixes 2003-04-14 12:20:24.000000000 -0700
+++ 25-akpm/fs/fat/inode.c 2003-04-14 12:20:24.000000000 -0700
@@ -608,7 +608,6 @@ struct dentry *fat_get_dentry(struct sup
return ERR_PTR(-ENOMEM);
}
result->d_op = sb->s_root->d_op;
- result->d_vfs_flags |= DCACHE_REFERENCED;
return result;
}
diff -puN fs/reiserfs/inode.c~DCACHE_REFERENCED-fixes fs/reiserfs/inode.c
--- 25/fs/reiserfs/inode.c~DCACHE_REFERENCED-fixes 2003-04-14 12:20:24.000000000 -0700
+++ 25-akpm/fs/reiserfs/inode.c 2003-04-14 12:20:24.000000000 -0700
@@ -1294,7 +1294,6 @@ struct dentry *reiserfs_get_dentry(struc
iput(inode);
return ERR_PTR(-ENOMEM);
}
- result->d_vfs_flags |= DCACHE_REFERENCED;
return result;
}
diff -puN fs/xfs/linux/xfs_super.c~DCACHE_REFERENCED-fixes fs/xfs/linux/xfs_super.c
--- 25/fs/xfs/linux/xfs_super.c~DCACHE_REFERENCED-fixes 2003-04-14 12:20:24.000000000 -0700
+++ 25-akpm/fs/xfs/linux/xfs_super.c 2003-04-14 12:20:24.000000000 -0700
@@ -741,7 +741,6 @@ linvfs_get_dentry(
iput(inode);
return ERR_PTR(-ENOMEM);
}
- result->d_vfs_flags |= DCACHE_REFERENCED;
return result;
}
diff -puN include/linux/dcache.h~DCACHE_REFERENCED-fixes include/linux/dcache.h
--- 25/include/linux/dcache.h~DCACHE_REFERENCED-fixes 2003-04-14 12:20:24.000000000 -0700
+++ 25-akpm/include/linux/dcache.h 2003-04-14 12:20:24.000000000 -0700
@@ -270,7 +270,6 @@ static inline struct dentry *dget(struct
if (!atomic_read(&dentry->d_count))
BUG();
atomic_inc(&dentry->d_count);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
}
return dentry;
}
_