linux/fs/exportfs/expfs.c

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/*
* 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/nfs/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(const struct path *path, char *name, struct dentry *child);
static int exportfs_get_name(struct vfsmount *mnt, struct dentry *dir,
char *name, struct dentry *child)
{
const struct export_operations *nop = dir->d_sb->s_export_op;
struct path path = {.mnt = mnt, .dentry = dir};
if (nop->get_name)
return nop->get_name(dir, name, child);
else
return get_name(&path, 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),
void *context)
{
struct dentry *dentry, *toput = NULL;
struct inode *inode;
struct hlist_node *p;
if (acceptable(context, result))
return result;
inode = result->d_inode;
spin_lock(&inode->i_lock);
hlist_for_each_entry(dentry, p, &inode->i_dentry, d_alias) {
dget(dentry);
spin_unlock(&inode->i_lock);
if (toput)
dput(toput);
if (dentry != result && acceptable(context, dentry)) {
dput(result);
return dentry;
}
spin_lock(&inode->i_lock);
toput = dentry;
}
spin_unlock(&inode->i_lock);
if (toput)
dput(toput);
return NULL;
}
/*
* Find root of a disconnected subtree and return a reference to it.
*/
static struct dentry *
find_disconnected_root(struct dentry *dentry)
{
dget(dentry);
while (!IS_ROOT(dentry)) {
struct dentry *parent = dget_parent(dentry);
if (!(parent->d_flags & DCACHE_DISCONNECTED)) {
dput(parent);
break;
}
dput(dentry);
dentry = parent;
}
return dentry;
}
/*
* 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;
/*
* 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
*/
while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) {
struct dentry *pd = find_disconnected_root(target_dir);
if (!IS_ROOT(pd)) {
/* must have found a connected parent - great */
spin_lock(&pd->d_lock);
pd->d_flags &= ~DCACHE_DISCONNECTED;
spin_unlock(&pd->d_lock);
noprogress = 0;
} 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;
spin_unlock(&pd->d_lock);
noprogress = 0;
} else {
/*
* 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 = ERR_PTR(-EACCES);
struct dentry *npd;
mutex_lock(&pd->d_inode->i_mutex);
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("%s: get_parent of %ld failed, err %d\n",
__func__, pd->d_inode->i_ino, err);
dput(pd);
break;
}
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);
if (err == -ENOENT)
/* some race between get_parent and
* get_name? just try again
*/
continue;
break;
}
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("%s: lookup failed: %d\n",
__func__, err);
dput(ppd);
dput(pd);
break;
}
/* we didn't really want npd, we really wanted
* a side-effect of the lookup.
* hopefully, npd == pd, though it isn't really
* a problem if it isn't
*/
if (npd == pd)
noprogress = 0;
else
printk("%s: npd != pd\n", __func__);
dput(npd);
dput(ppd);
if (IS_ROOT(pd)) {
/* something went wrong, we have to give up */
dput(pd);
break;
}
}
dput(pd);
}
if (target_dir->d_flags & DCACHE_DISCONNECTED) {
/* something went wrong - oh-well */
if (!err)
err = -ESTALE;
return err;
}
return 0;
}
struct getdents_callback {
char *name; /* name that was found. It already points to a
buffer NAME_MAX+1 is size */
unsigned long ino; /* the inum we are looking for */
int found; /* inode matched? */
int sequence; /* sequence counter */
};
/*
* A rather strange filldir function to capture
* the name matching the specified inode number.
*/
static int filldir_one(void * __buf, const char * name, int len,
[PATCH] VFS: Make filldir_t and struct kstat deal in 64-bit inode numbers These patches make the kernel pass 64-bit inode numbers internally when communicating to userspace, even on a 32-bit system. They are required because some filesystems have intrinsic 64-bit inode numbers: NFS3+ and XFS for example. The 64-bit inode numbers are then propagated to userspace automatically where the arch supports it. Problems have been seen with userspace (eg: ld.so) using the 64-bit inode number returned by stat64() or getdents64() to differentiate files, and failing because the 64-bit inode number space was compressed to 32-bits, and so overlaps occur. This patch: Make filldir_t take a 64-bit inode number and struct kstat carry a 64-bit inode number so that 64-bit inode numbers can be passed back to userspace. The stat functions then returns the full 64-bit inode number where available and where possible. If it is not possible to represent the inode number supplied by the filesystem in the field provided by userspace, then error EOVERFLOW will be issued. Similarly, the getdents/readdir functions now pass the full 64-bit inode number to userspace where possible, returning EOVERFLOW instead when a directory entry is encountered that can't be properly represented. Note that this means that some inodes will not be stat'able on a 32-bit system with old libraries where they were before - but it does mean that there will be no ambiguity over what a 32-bit inode number refers to. Note similarly that directory scans may be cut short with an error on a 32-bit system with old libraries where the scan would work before for the same reasons. It is judged unlikely that this situation will occur because modern glibc uses 64-bit capable versions of stat and getdents class functions exclusively, and that older systems are unlikely to encounter unrepresentable inode numbers anyway. [akpm: alpha build fix] Signed-off-by: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-03 10:13:46 +02:00
loff_t pos, u64 ino, unsigned int d_type)
{
struct getdents_callback *buf = __buf;
int result = 0;
buf->sequence++;
if (buf->ino == ino) {
memcpy(buf->name, name, len);
buf->name[len] = '\0';
buf->found = 1;
result = -1;
}
return result;
}
/**
* get_name - default export_operations->get_name function
* @dentry: the directory in which to find a name
* @name: a pointer to a %NAME_MAX+1 char buffer to store the name
* @child: the dentry for the child directory.
*
* 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(const struct path *path, char *name, struct dentry *child)
{
const struct cred *cred = current_cred();
struct inode *dir = path->dentry->d_inode;
int error;
struct file *file;
struct getdents_callback buffer;
error = -ENOTDIR;
if (!dir || !S_ISDIR(dir->i_mode))
goto out;
error = -EINVAL;
if (!dir->i_fop)
goto out;
/*
* Open the directory ...
*/
file = dentry_open(path, O_RDONLY, cred);
error = PTR_ERR(file);
if (IS_ERR(file))
goto out;
error = -EINVAL;
if (!file->f_op->readdir)
goto out_close;
buffer.name = name;
buffer.ino = child->d_inode->i_ino;
buffer.found = 0;
buffer.sequence = 0;
while (1) {
int old_seq = buffer.sequence;
error = vfs_readdir(file, filldir_one, &buffer);
if (buffer.found) {
error = 0;
break;
}
if (error < 0)
break;
error = -ENOENT;
if (old_seq == buffer.sequence)
break;
}
out_close:
fput(file);
out:
return error;
}
/**
* export_encode_fh - default export_operations->encode_fh function
* @inode: the object to encode
* @fh: where to store the file handle fragment
* @max_len: maximum length to store there
* @parent: parent directory inode, if wanted
*
* This default encode_fh function assumes that the 32 inode number
* is suitable for locating an inode, and that the generation number
* 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 inode *inode, struct fid *fid,
int *max_len, struct inode *parent)
{
int len = *max_len;
exportfs: add fid type This patchset is a medium scale rewrite of the export operations interface. The goal is to make the interface less complex, and easier to understand from the filesystem side, aswell as preparing generic support for exporting of 64bit inode numbers. This touches all nfs exporting filesystems, and I've done testing on all of the filesystems I have here locally (xfs, ext2, ext3, reiserfs, jfs) This patch: Add a structured fid type so that we don't have to pass an array of u32 values around everywhere. It's a union of possible layouts. As a start there's only the u32 array and the traditional 32bit inode format, but there will be more in one of my next patchset when I start to document the various filehandle formats we have in lowlevel filesystems better. Also add an enum that gives the various filehandle types human- readable names. Note: Some people might think the struct containing an anonymous union is ugly, but I didn't want to pass around a raw union type. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22 01:42:03 +02:00
int type = FILEID_INO32_GEN;
if (parent && (len < 4)) {
*max_len = 4;
return 255;
} else if (len < 2) {
*max_len = 2;
return 255;
}
len = 2;
exportfs: add fid type This patchset is a medium scale rewrite of the export operations interface. The goal is to make the interface less complex, and easier to understand from the filesystem side, aswell as preparing generic support for exporting of 64bit inode numbers. This touches all nfs exporting filesystems, and I've done testing on all of the filesystems I have here locally (xfs, ext2, ext3, reiserfs, jfs) This patch: Add a structured fid type so that we don't have to pass an array of u32 values around everywhere. It's a union of possible layouts. As a start there's only the u32 array and the traditional 32bit inode format, but there will be more in one of my next patchset when I start to document the various filehandle formats we have in lowlevel filesystems better. Also add an enum that gives the various filehandle types human- readable names. Note: Some people might think the struct containing an anonymous union is ugly, but I didn't want to pass around a raw union type. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22 01:42:03 +02:00
fid->i32.ino = inode->i_ino;
fid->i32.gen = inode->i_generation;
if (parent) {
exportfs: add fid type This patchset is a medium scale rewrite of the export operations interface. The goal is to make the interface less complex, and easier to understand from the filesystem side, aswell as preparing generic support for exporting of 64bit inode numbers. This touches all nfs exporting filesystems, and I've done testing on all of the filesystems I have here locally (xfs, ext2, ext3, reiserfs, jfs) This patch: Add a structured fid type so that we don't have to pass an array of u32 values around everywhere. It's a union of possible layouts. As a start there's only the u32 array and the traditional 32bit inode format, but there will be more in one of my next patchset when I start to document the various filehandle formats we have in lowlevel filesystems better. Also add an enum that gives the various filehandle types human- readable names. Note: Some people might think the struct containing an anonymous union is ugly, but I didn't want to pass around a raw union type. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22 01:42:03 +02:00
fid->i32.parent_ino = parent->i_ino;
fid->i32.parent_gen = parent->i_generation;
len = 4;
exportfs: add fid type This patchset is a medium scale rewrite of the export operations interface. The goal is to make the interface less complex, and easier to understand from the filesystem side, aswell as preparing generic support for exporting of 64bit inode numbers. This touches all nfs exporting filesystems, and I've done testing on all of the filesystems I have here locally (xfs, ext2, ext3, reiserfs, jfs) This patch: Add a structured fid type so that we don't have to pass an array of u32 values around everywhere. It's a union of possible layouts. As a start there's only the u32 array and the traditional 32bit inode format, but there will be more in one of my next patchset when I start to document the various filehandle formats we have in lowlevel filesystems better. Also add an enum that gives the various filehandle types human- readable names. Note: Some people might think the struct containing an anonymous union is ugly, but I didn't want to pass around a raw union type. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22 01:42:03 +02:00
type = FILEID_INO32_GEN_PARENT;
}
*max_len = len;
return type;
}
exportfs: add fid type This patchset is a medium scale rewrite of the export operations interface. The goal is to make the interface less complex, and easier to understand from the filesystem side, aswell as preparing generic support for exporting of 64bit inode numbers. This touches all nfs exporting filesystems, and I've done testing on all of the filesystems I have here locally (xfs, ext2, ext3, reiserfs, jfs) This patch: Add a structured fid type so that we don't have to pass an array of u32 values around everywhere. It's a union of possible layouts. As a start there's only the u32 array and the traditional 32bit inode format, but there will be more in one of my next patchset when I start to document the various filehandle formats we have in lowlevel filesystems better. Also add an enum that gives the various filehandle types human- readable names. Note: Some people might think the struct containing an anonymous union is ugly, but I didn't want to pass around a raw union type. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22 01:42:03 +02:00
int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
int connectable)
{
const struct export_operations *nop = dentry->d_sb->s_export_op;
int error;
struct dentry *p = NULL;
struct inode *inode = dentry->d_inode, *parent = NULL;
if (connectable && !S_ISDIR(inode->i_mode)) {
p = dget_parent(dentry);
/*
* note that while p might've ceased to be our parent already,
* it's still pinned by and still positive.
*/
parent = p->d_inode;
}
if (nop->encode_fh)
error = nop->encode_fh(inode, fid->raw, max_len, parent);
else
error = export_encode_fh(inode, fid, max_len, parent);
dput(p);
return error;
}
EXPORT_SYMBOL_GPL(exportfs_encode_fh);
exportfs: add fid type This patchset is a medium scale rewrite of the export operations interface. The goal is to make the interface less complex, and easier to understand from the filesystem side, aswell as preparing generic support for exporting of 64bit inode numbers. This touches all nfs exporting filesystems, and I've done testing on all of the filesystems I have here locally (xfs, ext2, ext3, reiserfs, jfs) This patch: Add a structured fid type so that we don't have to pass an array of u32 values around everywhere. It's a union of possible layouts. As a start there's only the u32 array and the traditional 32bit inode format, but there will be more in one of my next patchset when I start to document the various filehandle formats we have in lowlevel filesystems better. Also add an enum that gives the various filehandle types human- readable names. Note: Some people might think the struct containing an anonymous union is ugly, but I didn't want to pass around a raw union type. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22 01:42:03 +02:00
struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
int fh_len, int fileid_type,
int (*acceptable)(void *, struct dentry *), void *context)
{
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.
*/
if (!nop || !nop->fh_to_dentry)
return ERR_PTR(-ESTALE);
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 (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 {
/*
* 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;
}
err_result:
dput(result);
return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(exportfs_decode_fh);
MODULE_LICENSE("GPL");