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Subject[PATCH] factor out duplicated code for handle2dentry conversation
Every filesystem that implements methods to convert from a NFS
filehandle to a dentry duplicates this code (there are even more out of
tree). Factor it out in common code. The function d_alloc_anon() is
already present in 2.5 with the same interface but a slightly different
implementation.

Also cleanup d_find_alias (that has a very similar to d_alloc_anon and
yet not mergeable function body) to use proper list handling functions.


diff -uNr -Xdontdiff -p linux-2.4.20-pre4/fs/dcache.c linux/fs/dcache.c
--- linux-2.4.20-pre4/fs/dcache.c Sat Aug 17 14:54:38 2002
+++ linux/fs/dcache.c Tue Aug 20 11:39:48 2002
@@ -242,24 +242,22 @@ struct dentry * dget_locked(struct dentr

struct dentry * d_find_alias(struct inode *inode)
{
- struct list_head *head, *next, *tmp;
- struct dentry *alias;
+ struct dentry *dentry;
+ struct list_head *p;

spin_lock(&dcache_lock);
- head = &inode->i_dentry;
- next = inode->i_dentry.next;
- while (next != head) {
- tmp = next;
- next = tmp->next;
- alias = list_entry(tmp, struct dentry, d_alias);
- if (!list_empty(&alias->d_hash)) {
- __dget_locked(alias);
- spin_unlock(&dcache_lock);
- return alias;
- }
+ list_for_each(p, &inode->i_dentry) {
+ dentry = list_entry(p, struct dentry, d_alias);
+ if (!list_empty(&dentry->d_hash))
+ goto found;
}
spin_unlock(&dcache_lock);
return NULL;
+
+found:
+ __dget_locked(dentry);
+ spin_unlock(&dcache_lock);
+ return dentry;
}

/*
@@ -659,6 +657,53 @@ void d_instantiate(struct dentry *entry,
}

/**
+ * d_alloc_anon - allocate an anonymous dentry
+ * @inode: inode to allocate the dentry for
+ *
+ * This is similar to d_alloc_root. It is used by filesystems when
+ * creating a dentry for a given inode, often in the process of
+ * mapping a filehandle to a dentry. The returned dentry may be
+ * anonymous, or may have a full name (if the inode was already
+ * in the cache). The file system may need to make further
+ * efforts to connect this dentry into the dcache properly.
+ *
+ * When called on a directory inode, we must ensure that
+ * the inode only ever has one dentry. If a dentry is
+ * found, that is returned instead of allocating a new one.
+ *
+ * On successful return, the reference to the inode has been transferred
+ * to the dentry. If %NULL is returned (indicating kmalloc failure),
+ * the reference on the inode has not been released.
+ */
+
+struct dentry * d_alloc_anon(struct inode *inode)
+{
+ struct dentry *dentry;
+ struct list_head *p;
+
+ /* Try to find a dentry. If possible, get a well-connected one. */
+ spin_lock(&dcache_lock);
+ list_for_each(p, &inode->i_dentry) {
+ dentry = list_entry(p, struct dentry, d_alias);
+ if (!(dentry->d_flags & DCACHE_NFSD_DISCONNECTED))
+ goto found;
+ }
+ spin_unlock(&dcache_lock);
+
+ /* Didn't find dentry. Create anonymous dcache entry. */
+ dentry = d_alloc_root(inode);
+ if (dentry)
+ dentry->d_flags |= DCACHE_NFSD_DISCONNECTED;
+ return dentry;
+
+found:
+ dget_locked(dentry);
+ spin_unlock(&dcache_lock);
+ iput(inode);
+ return dentry;
+}
+
+/**
* d_alloc_root - allocate root dentry
* @root_inode: inode to allocate the root for
*
diff -uNr -Xdontdiff -p linux-2.4.20-pre4/fs/fat/inode.c linux/fs/fat/inode.c
--- linux-2.4.20-pre4/fs/fat/inode.c Tue Aug 6 11:30:30 2002
+++ linux/fs/fat/inode.c Tue Aug 20 11:39:48 2002
@@ -430,7 +430,6 @@ struct dentry *fat_fh_to_dentry(struct s
int len, int fhtype, int parent)
{
struct inode *inode = NULL;
- struct list_head *lp;
struct dentry *result;

if (fhtype != 3)
@@ -477,33 +476,14 @@ struct dentry *fat_fh_to_dentry(struct s
if (!inode)
return ERR_PTR(-ESTALE);

-
- /* now to find a dentry.
- * If possible, get a well-connected one
- *
- * Given the way that we found the inode, it *MUST* be
- * well-connected, but it is easiest to just copy the
- * code.
- */
- spin_lock(&dcache_lock);
- for (lp = inode->i_dentry.next; lp != &inode->i_dentry ; lp=lp->next) {
- result = list_entry(lp,struct dentry, d_alias);
- if (! (result->d_flags & DCACHE_NFSD_DISCONNECTED)) {
- dget_locked(result);
- result->d_vfs_flags |= DCACHE_REFERENCED;
- spin_unlock(&dcache_lock);
- iput(inode);
- return result;
- }
- }
- spin_unlock(&dcache_lock);
- result = d_alloc_root(inode);
+
+ result = d_alloc_anon(inode);
if (result == NULL) {
iput(inode);
return ERR_PTR(-ENOMEM);
}
result->d_op = sb->s_root->d_op;
- result->d_flags |= DCACHE_NFSD_DISCONNECTED;
+ result->d_vfs_flags |= DCACHE_REFERENCED;
return result;


diff -uNr -Xdontdiff -p linux-2.4.20-pre4/fs/nfsd/nfsfh.c linux/fs/nfsd/nfsfh.c
--- linux-2.4.20-pre4/fs/nfsd/nfsfh.c Tue Aug 13 15:56:00 2002
+++ linux/fs/nfsd/nfsfh.c Tue Aug 20 11:39:48 2002
@@ -135,7 +135,6 @@ static struct dentry *nfsd_iget(struct s
* of 0 means "accept any"
*/
struct inode *inode;
- struct list_head *lp;
struct dentry *result;
if (ino == 0)
return ERR_PTR(-ESTALE);
@@ -155,27 +154,14 @@ static struct dentry *nfsd_iget(struct s
iput(inode);
return ERR_PTR(-ESTALE);
}
- /* now to find a dentry.
- * If possible, get a well-connected one
- */
- spin_lock(&dcache_lock);
- for (lp = inode->i_dentry.next; lp != &inode->i_dentry ; lp=lp->next) {
- result = list_entry(lp,struct dentry, d_alias);
- if (! (result->d_flags & DCACHE_NFSD_DISCONNECTED)) {
- dget_locked(result);
- result->d_vfs_flags |= DCACHE_REFERENCED;
- spin_unlock(&dcache_lock);
- iput(inode);
- return result;
- }
- }
- spin_unlock(&dcache_lock);
- result = d_alloc_root(inode);
+
+
+ result = d_alloc_anon(inode);
if (result == NULL) {
iput(inode);
return ERR_PTR(-ENOMEM);
}
- result->d_flags |= DCACHE_NFSD_DISCONNECTED;
+ result->d_vfs_flags |= DCACHE_REFERENCED;
return result;
}

diff -uNr -Xdontdiff -p linux-2.4.20-pre4/fs/reiserfs/inode.c linux/fs/reiserfs/inode.c
--- linux-2.4.20-pre4/fs/reiserfs/inode.c Tue Aug 13 15:56:01 2002
+++ linux/fs/reiserfs/inode.c Tue Aug 20 11:39:48 2002
@@ -1229,7 +1229,6 @@ struct dentry *reiserfs_fh_to_dentry(str
int len, int fhtype, int parent) {
struct cpu_key key ;
struct inode *inode = NULL ;
- struct list_head *lp;
struct dentry *result;

/* fhtype happens to reflect the number of u32s encoded.
@@ -1281,27 +1280,12 @@ out:
if (!inode)
return ERR_PTR(-ESTALE) ;

- /* now to find a dentry.
- * If possible, get a well-connected one
- */
- spin_lock(&dcache_lock);
- for (lp = inode->i_dentry.next; lp != &inode->i_dentry ; lp=lp->next) {
- result = list_entry(lp,struct dentry, d_alias);
- if (! (result->d_flags & DCACHE_NFSD_DISCONNECTED)) {
- dget_locked(result);
- result->d_vfs_flags |= DCACHE_REFERENCED;
- spin_unlock(&dcache_lock);
- iput(inode);
- return result;
- }
- }
- spin_unlock(&dcache_lock);
- result = d_alloc_root(inode);
+ result = d_alloc_anon(inode);
if (result == NULL) {
iput(inode);
return ERR_PTR(-ENOMEM);
}
- result->d_flags |= DCACHE_NFSD_DISCONNECTED;
+ result->d_vfs_flags |= DCACHE_REFERENCED;
return result;

}
diff -uNr -Xdontdiff -p linux-2.4.20-pre4/include/linux/dcache.h linux/include/linux/dcache.h
--- linux-2.4.20-pre4/include/linux/dcache.h Tue Aug 6 11:30:41 2002
+++ linux/include/linux/dcache.h Tue Aug 20 15:26:38 2002
@@ -165,6 +165,7 @@ extern void d_delete(struct dentry *);

/* allocate/de-allocate */
extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
+extern struct dentry * d_alloc_anon(struct inode *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern int d_invalidate(struct dentry *);
diff -uNr -Xdontdiff -p linux-2.4.20-pre4/kernel/ksyms.c linux/kernel/ksyms.c
--- linux-2.4.20-pre4/kernel/ksyms.c Tue Aug 13 15:56:05 2002
+++ linux/kernel/ksyms.c Sun Aug 25 19:32:04 2002
@@ -162,6 +162,7 @@ EXPORT_SYMBOL(d_invalidate); /* May be i
EXPORT_SYMBOL(d_move);
EXPORT_SYMBOL(d_instantiate);
EXPORT_SYMBOL(d_alloc);
+EXPORT_SYMBOL(d_alloc_anon);
EXPORT_SYMBOL(d_lookup);
EXPORT_SYMBOL(__d_path);
EXPORT_SYMBOL(mark_buffer_dirty);
-
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