-
+/*
+ * Copyright (C) Neil Brown 2002
+ * Copyright (C) Christoph Hellwig 2007
+ *
+ * This file contains the code mapping from inodes to NFS file handles,
+ * and for mapping back from file handles to dentries.
+ *
+ * For details on why we do all the strange and hairy things in here
+ * take a look at Documentation/filesystems/Exporting.
+ */
#include <linux/exportfs.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
+#include <linux/sched.h>
#define dprintk(fmt, args...) do{}while(0)
-static int get_name(struct dentry *dentry, char *name,
+static int get_name(struct vfsmount *mnt, struct dentry *dentry, char *name,
struct dentry *child);
-static struct dentry *exportfs_get_dentry(struct super_block *sb, void *obj)
+static int exportfs_get_name(struct vfsmount *mnt, struct dentry *dir,
+ char *name, struct dentry *child)
{
- 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;
+ const 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);
+ return get_name(mnt, 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),
{
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);
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 = -ESTALE;
- struct export_operations *nops = sb->s_export_op;
- struct dentry *alias;
- int noprogress;
- char nbuf[NAME_MAX+1];
-
- /*
- * 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;
- }
-
- target_dir = dget(result);
- } else {
- if (acceptable(context, result))
- return result;
-
- alias = find_acceptable_alias(result, acceptable, context);
- if (alias)
- return alias;
+ 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);
+ }
+ spin_unlock(&dentry->d_lock);
+ return dentry;
+}
- 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;
- }
- }
+/*
+ * 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 vfsmount *mnt, struct dentry *target_dir, char *nbuf)
+{
+ int noprogress = 0;
+ int err = -ESTALE;
/*
- * 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.
- */
-
- /* 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 */
pd->d_flags &= ~DCACHE_DISCONNECTED;
spin_unlock(&pd->d_lock);
noprogress = 0;
- } else if (pd == sb->s_root) {
+ } else if (pd == mnt->mnt_sb->s_root) {
printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n");
spin_lock(&pd->d_lock);
pd->d_flags &= ~DCACHE_DISCONNECTED;
struct dentry *npd;
mutex_lock(&pd->d_inode->i_mutex);
- if (nops->get_parent)
- ppd = nops->get_parent(pd);
+ if (mnt->mnt_sb->s_export_op->get_parent)
+ ppd = mnt->mnt_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",
+ __func__, 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 = exportfs_get_name(ppd, nbuf, pd);
+
+ dprintk("%s: find name of %lu in %lu\n", __func__,
+ pd->d_inode->i_ino, ppd->d_inode->i_ino);
+ err = exportfs_get_name(mnt, ppd, nbuf, pd);
if (err) {
dput(ppd);
dput(pd);
continue;
break;
}
- dprintk("find_exported_dentry: found name: %s\n", nbuf);
+ dprintk("%s: found name: %s\n", __func__, 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",
+ __func__, err);
dput(ppd);
dput(pd);
break;
if (npd == pd)
noprogress = 0;
else
- printk("find_exported_dentry: npd != pd\n");
+ printk("%s: npd != pd\n", __func__);
dput(npd);
dput(ppd);
if (IS_ROOT(pd)) {
/* 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 = 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));
- mutex_unlock(&target_dir->d_inode->i_mutex);
- if (!IS_ERR(nresult)) {
- if (nresult->d_inode) {
- dput(result);
- result = nresult;
- } else
- dput(nresult);
- }
- }
- }
- 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)
- return alias;
- /* drat - I just cannot find anything acceptable */
- 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
- * -EACCESS is safer
- */
- return ERR_PTR(-EACCES);
-
- err_target:
- dput(target_dir);
- err_result:
- dput(result);
- return ERR_PTR(err);
+ return 0;
}
struct getdents_callback {
* calls readdir on the parent until it finds an entry with
* the same inode number as the child, and returns that.
*/
-static int get_name(struct dentry *dentry, char *name,
- struct dentry *child)
+static int get_name(struct vfsmount *mnt, struct dentry *dentry,
+ char *name, struct dentry *child)
{
+ const struct cred *cred = current_cred();
struct inode *dir = dentry->d_inode;
int error;
struct file *file;
/*
* Open the directory ...
*/
- file = dentry_open(dget(dentry), NULL, O_RDONLY);
+ file = dentry_open(dget(dentry), mntget(mnt), O_RDONLY, cred);
error = PTR_ERR(file);
if (IS_ERR(file))
goto out;
int old_seq = buffer.sequence;
error = vfs_readdir(file, filldir_one, &buffer);
+ if (buffer.found) {
+ error = 0;
+ break;
+ }
if (error < 0)
break;
- error = 0;
- if (buffer.found)
- break;
error = -ENOENT;
if (old_seq == buffer.sequence)
break;
* can be used to check that it is still valid. It places them in the
* filehandle fragment where export_decode_fh expects to find them.
*/
-static int export_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
- int connectable)
+static int export_encode_fh(struct dentry *dentry, struct fid *fid,
+ int *max_len, int connectable)
{
struct inode * inode = dentry->d_inode;
int len = *max_len;
- int type = 1;
+ int type = FILEID_INO32_GEN;
if (len < 2 || (connectable && len < 4))
return 255;
len = 2;
- fh[0] = inode->i_ino;
- fh[1] = inode->i_generation;
+ fid->i32.ino = inode->i_ino;
+ fid->i32.gen = inode->i_generation;
if (connectable && !S_ISDIR(inode->i_mode)) {
struct inode *parent;
spin_lock(&dentry->d_lock);
parent = dentry->d_parent->d_inode;
- fh[2] = parent->i_ino;
- fh[3] = parent->i_generation;
+ fid->i32.parent_ino = parent->i_ino;
+ fid->i32.parent_gen = parent->i_generation;
spin_unlock(&dentry->d_lock);
len = 4;
- type = 2;
+ type = FILEID_INO32_GEN_PARENT;
}
*max_len = len;
return type;
}
-
-/**
- * export_decode_fh - default export_operations->decode_fh function
- * @sb: The superblock
- * @fh: pointer to the file handle fragment
- * @fh_len: length of file handle fragment
- * @acceptable: function for testing acceptability of dentrys
- * @context: context for @acceptable
- *
- * This is the default decode_fh() function.
- * a fileid_type of 1 indicates that the filehandlefragment
- * just contains an object identifier understood by get_dentry.
- * a fileid_type of 2 says that there is also a directory
- * identifier 8 bytes in to the filehandlefragement.
- */
-static struct dentry *export_decode_fh(struct super_block *sb, __u32 *fh, int fh_len,
- int fileid_type,
- int (*acceptable)(void *context, struct dentry *de),
- void *context)
-{
- __u32 parent[2];
- parent[0] = parent[1] = 0;
- if (fh_len < 2 || fileid_type > 2)
- return NULL;
- if (fileid_type == 2) {
- if (fh_len > 2) parent[0] = fh[2];
- if (fh_len > 3) parent[1] = fh[3];
- }
- return find_exported_dentry(sb, fh, parent,
- acceptable, context);
-}
-
-int exportfs_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
+int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
int connectable)
{
- struct export_operations *nop = dentry->d_sb->s_export_op;
+ const 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);
+ error = nop->encode_fh(dentry, fid->raw, max_len, connectable);
else
- error = export_encode_fh(dentry, fh, max_len, connectable);
+ error = export_encode_fh(dentry, fid, max_len, connectable);
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 dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
+ 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;
+ const struct export_operations *nop = mnt->mnt_sb->s_export_op;
+ struct dentry *result, *alias;
+ char nbuf[NAME_MAX+1];
+ int err;
+
+ /*
+ * Try to get any dentry for the given file handle from the filesystem.
+ */
+ result = nop->fh_to_dentry(mnt->mnt_sb, fid, fh_len, fileid_type);
+ if (!result)
+ result = ERR_PTR(-ESTALE);
+ if (IS_ERR(result))
+ return result;
- if (nop->decode_fh) {
- result = nop->decode_fh(mnt->mnt_sb, fh, fh_len, fileid_type,
- acceptable, context);
+ if (S_ISDIR(result->d_inode->i_mode)) {
+ /*
+ * This request is for a directory.
+ *
+ * On the positive side there is only one dentry for each
+ * directory inode. On the negative side this implies that we
+ * to ensure our dentry is connected all the way up to the
+ * filesystem root.
+ */
+ if (result->d_flags & DCACHE_DISCONNECTED) {
+ err = reconnect_path(mnt, result, nbuf);
+ if (err)
+ goto err_result;
+ }
+
+ if (!acceptable(context, result)) {
+ err = -EACCES;
+ goto err_result;
+ }
+
+ return result;
} else {
- result = export_decode_fh(mnt->mnt_sb, fh, fh_len, fileid_type,
- acceptable, context);
+ /*
+ * It's not a directory. Life is a little more complicated.
+ */
+ struct dentry *target_dir, *nresult;
+
+ /*
+ * See if either the dentry we just got from the filesystem
+ * or any alias for it is acceptable. This is always true
+ * if this filesystem is exported without the subtreecheck
+ * option. If the filesystem is exported with the subtree
+ * check option there's a fair chance we need to look at
+ * the parent directory in the file handle and make sure
+ * it's connected to the filesystem root.
+ */
+ alias = find_acceptable_alias(result, acceptable, context);
+ if (alias)
+ return alias;
+
+ /*
+ * Try to extract a dentry for the parent directory from the
+ * file handle. If this fails we'll have to give up.
+ */
+ err = -ESTALE;
+ if (!nop->fh_to_parent)
+ goto err_result;
+
+ target_dir = nop->fh_to_parent(mnt->mnt_sb, fid,
+ fh_len, fileid_type);
+ if (!target_dir)
+ goto err_result;
+ err = PTR_ERR(target_dir);
+ if (IS_ERR(target_dir))
+ goto err_result;
+
+ /*
+ * And as usual we need to make sure the parent directory is
+ * connected to the filesystem root. The VFS really doesn't
+ * like disconnected directories..
+ */
+ err = reconnect_path(mnt, target_dir, nbuf);
+ if (err) {
+ dput(target_dir);
+ goto err_result;
+ }
+
+ /*
+ * Now that we've got both a well-connected parent and a
+ * dentry for the inode we're after, make sure that our
+ * inode is actually connected to the parent.
+ */
+ err = exportfs_get_name(mnt, target_dir, nbuf, result);
+ if (!err) {
+ mutex_lock(&target_dir->d_inode->i_mutex);
+ 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) {
+ dput(result);
+ result = nresult;
+ } else
+ dput(nresult);
+ }
+ }
+
+ /*
+ * At this point we are done with the parent, but it's pinned
+ * by the child dentry anyway.
+ */
+ dput(target_dir);
+
+ /*
+ * And finally make sure the dentry is actually acceptable
+ * to NFSD.
+ */
+ alias = find_acceptable_alias(result, acceptable, context);
+ if (!alias) {
+ err = -EACCES;
+ goto err_result;
+ }
+
+ return alias;
}
- return result;
+ err_result:
+ dput(result);
+ return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(exportfs_decode_fh);
-EXPORT_SYMBOL(find_exported_dentry);
-
MODULE_LICENSE("GPL");
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff