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-rw-r--r--fs/exportfs/expfs.c439
1 files changed, 220 insertions, 219 deletions
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index e98f6cd7200..8adb32a9387 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -1,15 +1,45 @@
+#include <linux/exportfs.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/module.h>
+#include <linux/mount.h>
#include <linux/namei.h>
-struct export_operations export_op_default;
+#define dprintk(fmt, args...) do{}while(0)
-#define CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
-#define dprintk(fmt, args...) do{}while(0)
+static int get_name(struct dentry *dentry, char *name,
+ struct dentry *child);
+
+
+static struct dentry *exportfs_get_dentry(struct super_block *sb, void *obj)
+{
+ struct dentry *result = ERR_PTR(-ESTALE);
+
+ if (sb->s_export_op->get_dentry) {
+ result = sb->s_export_op->get_dentry(sb, obj);
+ if (!result)
+ result = ERR_PTR(-ESTALE);
+ }
+
+ return result;
+}
+
+static int exportfs_get_name(struct dentry *dir, char *name,
+ struct dentry *child)
+{
+ struct export_operations *nop = dir->d_sb->s_export_op;
+ if (nop->get_name)
+ return nop->get_name(dir, name, child);
+ else
+ return get_name(dir, name, child);
+}
+
+/*
+ * Check if the dentry or any of it's aliases is acceptable.
+ */
static struct dentry *
find_acceptable_alias(struct dentry *result,
int (*acceptable)(void *context, struct dentry *dentry),
@@ -17,6 +47,9 @@ find_acceptable_alias(struct dentry *result,
{
struct dentry *dentry, *toput = NULL;
+ if (acceptable(context, result))
+ return result;
+
spin_lock(&dcache_lock);
list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
dget_locked(dentry);
@@ -37,130 +70,50 @@ find_acceptable_alias(struct dentry *result,
return NULL;
}
-/**
- * find_exported_dentry - helper routine to implement export_operations->decode_fh
- * @sb: The &super_block identifying the filesystem
- * @obj: An opaque identifier of the object to be found - passed to
- * get_inode
- * @parent: An optional opqaue identifier of the parent of the object.
- * @acceptable: A function used to test possible &dentries to see if they are
- * acceptable
- * @context: A parameter to @acceptable so that it knows on what basis to
- * judge.
- *
- * find_exported_dentry is the central helper routine to enable file systems
- * to provide the decode_fh() export_operation. It's main task is to take
- * an &inode, find or create an appropriate &dentry structure, and possibly
- * splice this into the dcache in the correct place.
- *
- * The decode_fh() operation provided by the filesystem should call
- * find_exported_dentry() with the same parameters that it received except
- * that instead of the file handle fragment, pointers to opaque identifiers
- * for the object and optionally its parent are passed. The default decode_fh
- * routine passes one pointer to the start of the filehandle fragment, and
- * one 8 bytes into the fragment. It is expected that most filesystems will
- * take this approach, though the offset to the parent identifier may well be
- * different.
- *
- * find_exported_dentry() will call get_dentry to get an dentry pointer from
- * the file system. If any &dentry in the d_alias list is acceptable, it will
- * be returned. Otherwise find_exported_dentry() will attempt to splice a new
- * &dentry into the dcache using get_name() and get_parent() to find the
- * appropriate place.
+/*
+ * Find root of a disconnected subtree and return a reference to it.
*/
-
-struct dentry *
-find_exported_dentry(struct super_block *sb, void *obj, void *parent,
- int (*acceptable)(void *context, struct dentry *de),
- void *context)
+static struct dentry *
+find_disconnected_root(struct dentry *dentry)
{
- struct dentry *result = NULL;
- struct dentry *target_dir;
- int err;
- struct export_operations *nops = sb->s_export_op;
- struct dentry *alias;
- int noprogress;
- char nbuf[NAME_MAX+1];
-
- /*
- * Attempt to find the inode.
- */
- result = CALL(sb->s_export_op,get_dentry)(sb,obj);
- err = -ESTALE;
- if (result == NULL)
- goto err_out;
- if (IS_ERR(result)) {
- err = PTR_ERR(result);
- goto err_out;
+ dget(dentry);
+ spin_lock(&dentry->d_lock);
+ while (!IS_ROOT(dentry) &&
+ (dentry->d_parent->d_flags & DCACHE_DISCONNECTED)) {
+ struct dentry *parent = dentry->d_parent;
+ dget(parent);
+ spin_unlock(&dentry->d_lock);
+ dput(dentry);
+ dentry = parent;
+ spin_lock(&dentry->d_lock);
}
- if (S_ISDIR(result->d_inode->i_mode) &&
- (result->d_flags & DCACHE_DISCONNECTED)) {
- /* it is an unconnected directory, we must connect it */
- ;
- } else {
- if (acceptable(context, result))
- return result;
- if (S_ISDIR(result->d_inode->i_mode)) {
- err = -EACCES;
- goto err_result;
- }
+ spin_unlock(&dentry->d_lock);
+ return dentry;
+}
- alias = find_acceptable_alias(result, acceptable, context);
- if (alias)
- return alias;
- }
-
- /* It's a directory, or we are required to confirm the file's
- * location in the tree based on the parent information
- */
- dprintk("find_exported_dentry: need to look harder for %s/%d\n",sb->s_id,*(int*)obj);
- if (S_ISDIR(result->d_inode->i_mode))
- target_dir = dget(result);
- else {
- if (parent == NULL)
- goto err_result;
- target_dir = CALL(sb->s_export_op,get_dentry)(sb,parent);
- if (IS_ERR(target_dir))
- err = PTR_ERR(target_dir);
- if (target_dir == NULL || IS_ERR(target_dir))
- goto err_result;
- }
- /*
- * Now we need to make sure that target_dir is properly connected.
- * It may already be, as the flag isn't always updated when connection
- * happens.
- * So, we walk up parent links until we find a connected directory,
- * or we run out of directories. Then we find the parent, find
- * the name of the child in that parent, and do a lookup.
- * This should connect the child into the parent
- * We then repeat.
- */
+/*
+ * Make sure target_dir is fully connected to the dentry tree.
+ *
+ * It may already be, as the flag isn't always updated when connection happens.
+ */
+static int
+reconnect_path(struct super_block *sb, struct dentry *target_dir)
+{
+ char nbuf[NAME_MAX+1];
+ int noprogress = 0;
+ int err = -ESTALE;
- /* it is possible that a confused file system might not let us complete
+ /*
+ * It is possible that a confused file system might not let us complete
* the path to the root. For example, if get_parent returns a directory
* in which we cannot find a name for the child. While this implies a
* very sick filesystem we don't want it to cause knfsd to spin. Hence
* the noprogress counter. If we go through the loop 10 times (2 is
* probably enough) without getting anywhere, we just give up
*/
- noprogress= 0;
while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) {
- struct dentry *pd = target_dir;
-
- dget(pd);
- spin_lock(&pd->d_lock);
- while (!IS_ROOT(pd) &&
- (pd->d_parent->d_flags&DCACHE_DISCONNECTED)) {
- struct dentry *parent = pd->d_parent;
-
- dget(parent);
- spin_unlock(&pd->d_lock);
- dput(pd);
- pd = parent;
- spin_lock(&pd->d_lock);
- }
- spin_unlock(&pd->d_lock);
+ struct dentry *pd = find_disconnected_root(target_dir);
if (!IS_ROOT(pd)) {
/* must have found a connected parent - great */
@@ -175,29 +128,40 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
spin_unlock(&pd->d_lock);
noprogress = 0;
} else {
- /* we have hit the top of a disconnected path. Try
- * to find parent and connect
- * note: racing with some other process renaming a
- * directory isn't much of a problem here. If someone
- * renames the directory, it will end up properly
- * connected, which is what we want
+ /*
+ * We have hit the top of a disconnected path, try to
+ * find parent and connect.
+ *
+ * Racing with some other process renaming a directory
+ * isn't much of a problem here. If someone renames
+ * the directory, it will end up properly connected,
+ * which is what we want
+ *
+ * Getting the parent can't be supported generically,
+ * the locking is too icky.
+ *
+ * Instead we just return EACCES. If server reboots
+ * or inodes get flushed, you lose
*/
- struct dentry *ppd;
+ struct dentry *ppd = ERR_PTR(-EACCES);
struct dentry *npd;
mutex_lock(&pd->d_inode->i_mutex);
- ppd = CALL(nops,get_parent)(pd);
+ if (sb->s_export_op->get_parent)
+ ppd = sb->s_export_op->get_parent(pd);
mutex_unlock(&pd->d_inode->i_mutex);
if (IS_ERR(ppd)) {
err = PTR_ERR(ppd);
- dprintk("find_exported_dentry: get_parent of %ld failed, err %d\n",
- pd->d_inode->i_ino, err);
+ dprintk("%s: get_parent of %ld failed, err %d\n",
+ __FUNCTION__, pd->d_inode->i_ino, err);
dput(pd);
break;
}
- dprintk("find_exported_dentry: find name of %lu in %lu\n", pd->d_inode->i_ino, ppd->d_inode->i_ino);
- err = CALL(nops,get_name)(ppd, nbuf, pd);
+
+ dprintk("%s: find name of %lu in %lu\n", __FUNCTION__,
+ pd->d_inode->i_ino, ppd->d_inode->i_ino);
+ err = exportfs_get_name(ppd, nbuf, pd);
if (err) {
dput(ppd);
dput(pd);
@@ -208,13 +172,14 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
continue;
break;
}
- dprintk("find_exported_dentry: found name: %s\n", nbuf);
+ dprintk("%s: found name: %s\n", __FUNCTION__, nbuf);
mutex_lock(&ppd->d_inode->i_mutex);
npd = lookup_one_len(nbuf, ppd, strlen(nbuf));
mutex_unlock(&ppd->d_inode->i_mutex);
if (IS_ERR(npd)) {
err = PTR_ERR(npd);
- dprintk("find_exported_dentry: lookup failed: %d\n", err);
+ dprintk("%s: lookup failed: %d\n",
+ __FUNCTION__, err);
dput(ppd);
dput(pd);
break;
@@ -227,7 +192,7 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
if (npd == pd)
noprogress = 0;
else
- printk("find_exported_dentry: npd != pd\n");
+ printk("%s: npd != pd\n", __FUNCTION__);
dput(npd);
dput(ppd);
if (IS_ROOT(pd)) {
@@ -243,15 +208,101 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
/* something went wrong - oh-well */
if (!err)
err = -ESTALE;
- goto err_target;
+ return err;
}
- /* if we weren't after a directory, have one more step to go */
- if (result != target_dir) {
- struct dentry *nresult;
- err = CALL(nops,get_name)(target_dir, nbuf, result);
+
+ return 0;
+}
+
+/**
+ * find_exported_dentry - helper routine to implement export_operations->decode_fh
+ * @sb: The &super_block identifying the filesystem
+ * @obj: An opaque identifier of the object to be found - passed to
+ * get_inode
+ * @parent: An optional opqaue identifier of the parent of the object.
+ * @acceptable: A function used to test possible &dentries to see if they are
+ * acceptable
+ * @context: A parameter to @acceptable so that it knows on what basis to
+ * judge.
+ *
+ * find_exported_dentry is the central helper routine to enable file systems
+ * to provide the decode_fh() export_operation. It's main task is to take
+ * an &inode, find or create an appropriate &dentry structure, and possibly
+ * splice this into the dcache in the correct place.
+ *
+ * The decode_fh() operation provided by the filesystem should call
+ * find_exported_dentry() with the same parameters that it received except
+ * that instead of the file handle fragment, pointers to opaque identifiers
+ * for the object and optionally its parent are passed. The default decode_fh
+ * routine passes one pointer to the start of the filehandle fragment, and
+ * one 8 bytes into the fragment. It is expected that most filesystems will
+ * take this approach, though the offset to the parent identifier may well be
+ * different.
+ *
+ * find_exported_dentry() will call get_dentry to get an dentry pointer from
+ * the file system. If any &dentry in the d_alias list is acceptable, it will
+ * be returned. Otherwise find_exported_dentry() will attempt to splice a new
+ * &dentry into the dcache using get_name() and get_parent() to find the
+ * appropriate place.
+ */
+
+struct dentry *
+find_exported_dentry(struct super_block *sb, void *obj, void *parent,
+ int (*acceptable)(void *context, struct dentry *de),
+ void *context)
+{
+ struct dentry *result, *alias;
+ int err = -ESTALE;
+
+ /*
+ * Attempt to find the inode.
+ */
+ result = exportfs_get_dentry(sb, obj);
+ if (IS_ERR(result))
+ return result;
+
+ if (S_ISDIR(result->d_inode->i_mode)) {
+ if (!(result->d_flags & DCACHE_DISCONNECTED)) {
+ if (acceptable(context, result))
+ return result;
+ err = -EACCES;
+ goto err_result;
+ }
+
+ err = reconnect_path(sb, result);
+ if (err)
+ goto err_result;
+ } else {
+ struct dentry *target_dir, *nresult;
+ char nbuf[NAME_MAX+1];
+
+ alias = find_acceptable_alias(result, acceptable, context);
+ if (alias)
+ return alias;
+
+ if (parent == NULL)
+ goto err_result;
+
+ target_dir = exportfs_get_dentry(sb,parent);
+ if (IS_ERR(target_dir)) {
+ err = PTR_ERR(target_dir);
+ goto err_result;
+ }
+
+ err = reconnect_path(sb, target_dir);
+ if (err) {
+ dput(target_dir);
+ goto err_result;
+ }
+
+ /*
+ * As we weren't after a directory, have one more step to go.
+ */
+ err = exportfs_get_name(target_dir, nbuf, result);
if (!err) {
mutex_lock(&target_dir->d_inode->i_mutex);
- nresult = lookup_one_len(nbuf, target_dir, strlen(nbuf));
+ nresult = lookup_one_len(nbuf, target_dir,
+ strlen(nbuf));
mutex_unlock(&target_dir->d_inode->i_mutex);
if (!IS_ERR(nresult)) {
if (nresult->d_inode) {
@@ -261,11 +312,8 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
dput(nresult);
}
}
+ dput(target_dir);
}
- dput(target_dir);
- /* now result is properly connected, it is our best bet */
- if (acceptable(context, result))
- return result;
alias = find_acceptable_alias(result, acceptable, context);
if (alias)
@@ -275,32 +323,16 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
dput(result);
/* It might be justifiable to return ESTALE here,
* but the filehandle at-least looks reasonable good
- * and it just be a permission problem, so returning
+ * and it may just be a permission problem, so returning
* -EACCESS is safer
*/
return ERR_PTR(-EACCES);
- err_target:
- dput(target_dir);
err_result:
dput(result);
- err_out:
return ERR_PTR(err);
}
-
-
-static struct dentry *get_parent(struct dentry *child)
-{
- /* get_parent cannot be supported generically, the locking
- * is too icky.
- * instead, we just return EACCES. If server reboots or inodes
- * get flushed, you lose
- */
- return ERR_PTR(-EACCES);
-}
-
-
struct getdents_callback {
char *name; /* name that was found. It already points to a
buffer NAME_MAX+1 is size */
@@ -390,61 +422,6 @@ out:
return error;
}
-
-static struct dentry *export_iget(struct super_block *sb, unsigned long ino, __u32 generation)
-{
-
- /* iget isn't really right if the inode is currently unallocated!!
- * This should really all be done inside each filesystem
- *
- * ext2fs' read_inode has been strengthed to return a bad_inode if
- * the inode had been deleted.
- *
- * Currently we don't know the generation for parent directory, so
- * a generation of 0 means "accept any"
- */
- struct inode *inode;
- struct dentry *result;
- if (ino == 0)
- return ERR_PTR(-ESTALE);
- inode = iget(sb, ino);
- if (inode == NULL)
- return ERR_PTR(-ENOMEM);
- if (is_bad_inode(inode)
- || (generation && inode->i_generation != generation)
- ) {
- /* we didn't find the right inode.. */
- dprintk("fh_verify: Inode %lu, Bad count: %d %d or version %u %u\n",
- inode->i_ino,
- inode->i_nlink, atomic_read(&inode->i_count),
- inode->i_generation,
- generation);
-
- iput(inode);
- return ERR_PTR(-ESTALE);
- }
- /* now to find a dentry.
- * If possible, get a well-connected one
- */
- result = d_alloc_anon(inode);
- if (!result) {
- iput(inode);
- return ERR_PTR(-ENOMEM);
- }
- return result;
-}
-
-
-static struct dentry *get_object(struct super_block *sb, void *vobjp)
-{
- __u32 *objp = vobjp;
- unsigned long ino = objp[0];
- __u32 generation = objp[1];
-
- return export_iget(sb, ino, generation);
-}
-
-
/**
* export_encode_fh - default export_operations->encode_fh function
* @dentry: the dentry to encode
@@ -517,16 +494,40 @@ static struct dentry *export_decode_fh(struct super_block *sb, __u32 *fh, int fh
acceptable, context);
}
-struct export_operations export_op_default = {
- .decode_fh = export_decode_fh,
- .encode_fh = export_encode_fh,
+int exportfs_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
+ int connectable)
+{
+ struct export_operations *nop = dentry->d_sb->s_export_op;
+ int error;
+
+ if (nop->encode_fh)
+ error = nop->encode_fh(dentry, fh, max_len, connectable);
+ else
+ error = export_encode_fh(dentry, fh, max_len, connectable);
- .get_name = get_name,
- .get_parent = get_parent,
- .get_dentry = get_object,
-};
+ return error;
+}
+EXPORT_SYMBOL_GPL(exportfs_encode_fh);
+
+struct dentry *exportfs_decode_fh(struct vfsmount *mnt, __u32 *fh, int fh_len,
+ int fileid_type, int (*acceptable)(void *, struct dentry *),
+ void *context)
+{
+ struct export_operations *nop = mnt->mnt_sb->s_export_op;
+ struct dentry *result;
+
+ if (nop->decode_fh) {
+ result = nop->decode_fh(mnt->mnt_sb, fh, fh_len, fileid_type,
+ acceptable, context);
+ } else {
+ result = export_decode_fh(mnt->mnt_sb, fh, fh_len, fileid_type,
+ acceptable, context);
+ }
+
+ return result;
+}
+EXPORT_SYMBOL_GPL(exportfs_decode_fh);
-EXPORT_SYMBOL(export_op_default);
EXPORT_SYMBOL(find_exported_dentry);
MODULE_LICENSE("GPL");