/*
* namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS
* project.
*
* Copyright (c) 2001-2006 Anton Altaparmakov
*
* This program/include file is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program/include file is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (in the main directory of the Linux-NTFS
* distribution in the file COPYING); if not, write to the Free Software
* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/dcache.h>
#include <linux/security.h>
#include "attrib.h"
#include "debug.h"
#include "dir.h"
#include "mft.h"
#include "ntfs.h"
/**
* ntfs_lookup - find the inode represented by a dentry in a directory inode
* @dir_ino: directory inode in which to look for the inode
* @dent: dentry representing the inode to look for
* @nd: lookup nameidata
*
* In short, ntfs_lookup() looks for the inode represented by the dentry @dent
* in the directory inode @dir_ino and if found attaches the inode to the
* dentry @dent.
*
* In more detail, the dentry @dent specifies which inode to look for by
* supplying the name of the inode in @dent->d_name.name. ntfs_lookup()
* converts the name to Unicode and walks the contents of the directory inode
* @dir_ino looking for the converted Unicode name. If the name is found in the
* directory, the corresponding inode is loaded by calling ntfs_iget() on its
* inode number and the inode is associated with the dentry @dent via a call to
* d_splice_alias().
*
* If the name is not found in the directory, a NULL inode is inserted into the
* dentry @dent via a call to d_add(). The dentry is then termed a negative
* dentry.
*
* Only if an actual error occurs, do we return an error via ERR_PTR().
*
* In order to handle the case insensitivity issues of NTFS with regards to the
* dcache and the dcache requiring only one dentry per directory, we deal with
* dentry aliases that only differ in case in ->ntfs_lookup() while maintaining
* a case sensitive dcache. This means that we get the full benefit of dcache
* speed when the file/directory is looked up with the same case as returned by
* ->ntfs_readdir() but that a lookup for any other case (or for the short file
* name) will not find anything in dcache and will enter ->ntfs_lookup()
* instead, where we search the directory for a fully matching file name
* (including case) and if that is not found, we search for a file name that
* matches with different case and if that has non-POSIX semantics we return
* that. We actually do only one search (case sensitive) and keep tabs on
* whether we have found a case insensitive match in the process.
*
* To simplify matters for us, we do not treat the short vs long filenames as
* two hard links but instead if the lookup matches a short filename, we
* return the dentry for the corresponding long filename instead.
*
* There are three cases we need to distinguish here:
*
* 1) @dent perfectly matches (i.e. including case) a directory entry with a
* file name in the WIN32 or POSIX namespaces. In this case
* ntfs_lookup_inode_by_name() will return with name set to NULL and we
* just d_splice_alias() @dent.
* 2) @dent matches (not including case) a directory entry with a file name in
* the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return
* with name set to point to a kmalloc()ed ntfs_name structure containing
* the properly cased little endian Unicode name. We convert the name to the
* current NLS code page, search if a dentry with this name already exists
* and if so return that instead of @dent. At this point things are
* complicated by the possibility of 'disconnected' dentries due to NFS
* which we deal with appropriately (see the code comments). The VFS will
* then destroy the old @dent and use the one we returned. If a dentry is
* not found, we allocate a new one, d_splice_alias() it, and return it as
* above.
* 3) @dent matches either perfectly or not (i.e. we don't care about case) a
* directory entry with a file name in the DOS namespace. In this case
* ntfs_lookup_inode_by_name() will return with name set to point to a
* kmalloc()ed ntfs_name structure containing the mft reference (cpu endian)
* of the inode. We use the mft reference to read the inode and to find the
* file name in the WIN32 namespace corresponding to the matched short file
* name. We then convert the name to the current NLS code page, and proceed
* searching for a dentry with this name, etc, as in case 2), above.
*
* Locking: Caller must hold i_mutex on the directory.
*/
static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent,
struct nameidata *nd)
{
ntfs_volume *vol = NTFS_SB(dir_ino->i_sb);
struct inode *dent_inode;
ntfschar *uname;
ntfs_name *name = NULL;
MFT_REF mref;
unsigned long dent_ino;
int uname_len;
ntfs_debug("Looking up %s in directory inode 0x%lx.",
dent->d_name.name, dir_ino->i_ino);
/* Convert the name of the dentry to Unicode. */
uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len,
&uname);
if (uname_len < 0) {
ntfs_error(vol->sb, "Failed to convert name to Unicode.");
return ERR_PTR(uname_len);
}
mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len,
&name);
kmem_cache_free(ntfs_name_cache, uname);
if (!IS_ERR_MREF(mref)) {
dent_ino = MREF(mref);
ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino);
dent_inode = ntfs_iget(vol->sb, dent_ino);
if (likely(!IS_ERR(dent_inode))) {
/* Consistency check. */
if (is_bad_inode(dent_inode) || MSEQNO(mref) ==
NTFS_I(dent_inode)->seq_no ||
dent_ino == FILE_MFT) {
/* Perfect WIN32/POSIX match. -- Case 1. */
if (!name) {
ntfs_debug("Done. (Case 1.)");
return d_splice_alias(dent_inode, dent);
}
/*
* We are too indented. Handle imperfect
* matches and short file names further below.
*/
goto handle_name;
}
ntfs_error(vol->sb, "Found stale reference to inode "
"0x%lx (reference sequence number = "
"0x%x, inode sequence number = 0x%x), "
"returning -EIO. Run chkdsk.",
dent_ino, MSEQNO(mref),
NTFS_I(dent_inode)->seq_no);
iput(dent_inode);
dent_inode = ERR_PTR(-EIO);
} else
ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with "
"error code %li.", dent_ino,
PTR_ERR(dent_inode));
kfree(name);
/* Return the error code. */
return (struct dentry *)dent_inode;
}
/* It is guaranteed that name is no longer allocated at this point. */
if (MREF_ERR(mref) == -ENOENT) {
ntfs_debug("Entry was not found, adding negative dentry.");
/* The dcache will handle negative entries. */
d_add(dent, NULL);
ntfs_debug("Done.");
return NULL;
}
ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error "
"code %i.", -MREF_ERR(mref));
return ERR_PTR(MREF_ERR(mref));
// TODO: Consider moving this lot to a separate function! (AIA)
handle_name:
{
struct dentry *real_dent, *new_dent;
MFT_RECORD *m;
ntfs_attr_search_ctx *ctx;
ntfs_inode *ni = NTFS_I(dent_inode);
int err;
struct qstr nls_name;
nls_name.name = NULL;
if (name->type != FILE_NAME_DOS) { /* Case 2. */
ntfs_debug("Case 2.");
nls_name.len = (unsigned)ntfs_ucstonls(vol,
(ntfschar*)&name->name, name->len,
(unsigned char**)&nls_name.name, 0);
kfree(name);
} else /* if (name->type == FILE_NAME_DOS) */ { /* Case 3. */
FILE_NAME_ATTR *fn;
ntfs_debug("Case 3.");
kfree(name);
/* Find the WIN32 name corresponding to the matched DOS name. */
ni = NTFS_I(dent_inode);
m = map_mft_record(ni);
if (IS_ERR(m)) {
err = PTR_ERR(m);
m = NULL;
ctx = NULL;
goto err_out;
}
ctx = ntfs_attr_get_search_ctx(ni, m);
if (unlikely(!ctx)) {
err = -ENOMEM;
goto err_out;
}
do {
ATTR_RECORD *a;
u32 val_len;
err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0,
NULL, 0, ctx);
if (unlikely(err)) {
ntfs_error(vol->sb, "Inode corrupt: No WIN32 "
"namespace counterpart to DOS "
"file name. Run chkdsk.");
if (err == -ENOENT)
err = -EIO;
goto err_out;
}
/* Consistency checks. */
a = ctx->attr;
if (a->non_resident || a->flags)
goto eio_err_out;
val_len = le32_to_cpu(a->data.resident.value_length);
if (le16_to_cpu(a->data.resident.value_offset) +
val_len > le32_to_cpu(a->length))
goto eio_err_out;
fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu(
ctx->attr->data.resident.value_offset));
if ((u32)(fn->file_name_length * sizeof(ntfschar) +
sizeof(FILE_NAME_ATTR)) > val_len)
goto eio_err_out;
} while (fn->file_name_type != FILE_NAME_WIN32);
/* Convert the found WIN32 name to current NLS code page. */
nls_name.len = (unsigned)ntfs_ucstonls(vol,
(ntfschar*)&fn->file_name, fn->file_name_length,
(unsigned char**)&nls_name.name, 0);
ntfs_attr_put_search_ctx(ctx);
unmap_mft_record(ni);
}
m = NULL;
ctx = NULL;
/* Check if a conversion error occurred. */
if ((signed)nls_name.len < 0) {
err = (signed)nls_name.len;
goto err_out;
}
nls_name.hash = full_name_hash(nls_name.name, nls_name.len);
/*
* Note: No need for dent->d_lock lock as i_mutex is held on the
* parent inode.
*/
/* Does a dentry matching the nls_name exist already? */
real_dent = d_lookup(dent->d_parent, &nls_name);
/* If not, create it now. */
if (!real_dent) {
real_dent = d_alloc(dent->d_parent, &nls_name);
kfree(nls_name.name);
if (!real_dent) {
err = -ENOMEM;
goto err_out;
}
new_dent = d_splice_alias(dent_inode, real_dent);
if (new_dent)
dput(real_dent);
else
new_dent = real_dent;
ntfs_debug("Done. (Created new dentry.)");
return new_dent;
}
kfree(nls_name.name);
/* Matching dentry exists, check if it is negative. */
if (real_dent->d_inode) {
if (unlikely(real_dent->d_inode != dent_inode)) {
/* This can happen because bad inodes are unhashed. */
BUG_ON(!is_bad_inode(dent_inode));
BUG_ON(!is_bad_inode(real_dent->d_inode));
}
/*
* Already have the inode and the dentry attached, decrement
* the reference count to balance the ntfs_iget() we did
* earlier on. We found the dentry using d_lookup() so it
* cannot be disconnected and thus we do not need to worry
* about any NFS/disconnectedness issues here.
*/
iput(dent_inode);
ntfs_debug("Done. (Already had inode and dentry.)");
return real_dent;
}
/*
* Negative dentry: instantiate it unless the inode is a directory and
* has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED),
* in which case d_move() that in place of the found dentry.
*/
if (!S_ISDIR(dent_inode->i_mode)) {
/* Not a directory; everything is easy. */
d_instantiate(real_dent, dent_inode);
ntfs_debug("Done. (Already had negative file dentry.)");
return real_dent;
}
spin_lock(&dcache_lock);
if (list_empty(&dent_inode->i_dentry)) {
/*
* Directory without a 'disconnected' dentry; we need to do
* d_instantiate() by hand because it takes dcache_lock which
* we already hold.
*/
list_add(&real_dent->d_alias, &dent_inode->i_dentry);
real_dent->d_inode = dent_inode;
spin_unlock(&dcache_lock);
security_d_instantiate(real_dent, dent_inode);
ntfs_debug("Done. (Already had negative directory dentry.)");
return real_dent;
}
/*
* Directory with a 'disconnected' dentry; get a reference to the
* 'disconnected' dentry.
*/
new_dent = list_entry(dent_inode->i_dentry.next, struct dentry,
d_alias);
dget_locked(new_dent);
spin_unlock(&dcache_lock);
/* Do security vodoo. */
security_d_instantiate(real_dent, dent_inode);
/* Move new_dent in place of real_dent. */
d_move(new_dent, real_dent);
/* Balance the ntfs_iget() we did above. */
iput(dent_inode);
/* Throw away real_dent. */
dput(real_dent);
/* Use new_dent as the actual dentry. */
ntfs_debug("Done. (Already had negative, disconnected directory "
"dentry.)");
return new_dent;
eio_err_out:
ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk.");
err = -EIO;
err_out:
if (ctx)
ntfs_attr_put_search_ctx(ctx);
if (m)
unmap_mft_record(ni);
iput(dent_inode);
ntfs_error(vol->sb, "Failed, returning error code %i.", err);
return ERR_PTR(err);
}
}
/**
* Inode operations for directories.
*/
struct inode_operations ntfs_dir_inode_ops = {
.lookup = ntfs_lookup, /* VFS: Lookup directory. */
};
/**
* ntfs_get_parent - find the dentry of the parent of a given directory dentry
* @child_dent: dentry of the directory whose parent directory to find
*
* Find the dentry for the parent directory of the directory specified by the
* dentry @child_dent. This function is called from
* fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the
* default ->decode_fh() which is export_decode_fh() in the same file.
*
* The code is based on the ext3 ->get_parent() implementation found in
* fs/ext3/namei.c::ext3_get_parent().
*
* Note: ntfs_get_parent() is called with @child_dent->d_inode->i_mutex down.
*
* Return the dentry of the parent directory on success or the error code on
* error (IS_ERR() is true).
*/
static struct dentry *ntfs_get_parent(struct dentry *child_dent)
{
struct inode *vi = child_dent->d_inode;
ntfs_inode *ni = NTFS_I(vi);
MFT_RECORD *mrec;
ntfs_attr_search_ctx *ctx;
ATTR_RECORD *attr;
FILE_NAME_ATTR *fn;
struct inode *parent_vi;
struct dentry *parent_dent;
unsigned long parent_ino;
int err;
ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
/* Get the mft record of the inode belonging to the child dentry. */
mrec = map_mft_record(ni);
if (IS_ERR(mrec))
return (struct dentry *)mrec;
/* Find the first file name attribute in the mft record. */
ctx = ntfs_attr_get_search_ctx(ni, mrec);
if (unlikely(!ctx)) {
unmap_mft_record(ni);
return ERR_PTR(-ENOMEM);
}
try_next:
err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL,
0, ctx);
if (unlikely(err)) {
ntfs_attr_put_search_ctx(ctx);
unmap_mft_record(ni);
if (err == -ENOENT)
ntfs_error(vi->i_sb, "Inode 0x%lx does not have a "
"file name attribute. Run chkdsk.",
vi->i_ino);
return ERR_PTR(err);
}
attr = ctx->attr;
if (unlikely(attr->non_resident))
goto try_next;
fn = (FILE_NAME_ATTR *)((u8 *)attr +
le16_to_cpu(attr->data.resident.value_offset));
if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) >
(u8*)attr + le32_to_cpu(attr->length)))
goto try_next;
/* Get the inode number of the parent directory. */
parent_ino = MREF_LE(fn->parent_directory);
/* Release the search context and the mft record of the child. */
ntfs_attr_put_search_ctx(ctx);
unmap_mft_record(ni);
/* Get the inode of the parent directory. */
parent_vi = ntfs_iget(vi->i_sb, parent_ino);
if (IS_ERR(parent_vi) || unlikely(is_bad_inode(parent_vi))) {
if (!IS_ERR(parent_vi))
iput(parent_vi);
ntfs_error(vi->i_sb, "Failed to get parent directory inode "
"0x%lx of child inode 0x%lx.", parent_ino,
vi->i_ino);
return ERR_PTR(-EACCES);
}
/* Finally get a dentry for the parent directory and return it. */
parent_dent = d_alloc_anon(parent_vi);
if (unlikely(!parent_dent)) {
iput(parent_vi);
return ERR_PTR(-ENOMEM);
}
ntfs_debug("Done for inode 0x%lx.", vi->i_ino);
return parent_dent;
}
/**
* ntfs_get_dentry - find a dentry for the inode from a file handle sub-fragment
* @sb: super block identifying the mounted ntfs volume
* @fh: the file handle sub-fragment
*
* Find a dentry for the inode given a file handle sub-fragment. This function
* is called from fs/exportfs/expfs.c::find_exported_dentry() which in turn is
* called from the default ->decode_fh() which is export_decode_fh() in the
* same file. The code is closely based on the default ->get_dentry() helper
* fs/exportfs/expfs.c::get_object().
*
* The @fh contains two 32-bit unsigned values, the first one is the inode
* number and the second one is the inode generation.
*
* Return the dentry on success or the error code on error (IS_ERR() is true).
*/
static struct dentry *ntfs_get_dentry(struct super_block *sb, void *fh)
{
struct inode *vi;
struct dentry *dent;
unsigned long ino = ((u32 *)fh)[0];
u32 gen = ((u32 *)fh)[1];
ntfs_debug("Entering for inode 0x%lx, generation 0x%x.", ino, gen);
vi = ntfs_iget(sb, ino);
if (IS_ERR(vi)) {
ntfs_error(sb, "Failed to get inode 0x%lx.", ino);
return (struct dentry *)vi;
}
if (unlikely(is_bad_inode(vi) || vi->i_generation != gen)) {
/* We didn't find the right inode. */
ntfs_error(sb, "Inode 0x%lx, bad count: %d %d or version 0x%x "
"0x%x.", vi->i_ino, vi->i_nlink,
atomic_read(&vi->i_count), vi->i_generation,
gen);
iput(vi);
return ERR_PTR(-ESTALE);
}
/* Now find a dentry. If possible, get a well-connected one. */
dent = d_alloc_anon(vi);
if (unlikely(!dent)) {
iput(vi);
return ERR_PTR(-ENOMEM);
}
ntfs_debug("Done for inode 0x%lx, generation 0x%x.", ino, gen);
return dent;
}
/**
* Export operations allowing NFS exporting of mounted NTFS partitions.
*
* We use the default ->decode_fh() and ->encode_fh() for now. Note that they
* use 32 bits to store the inode number which is an unsigned long so on 64-bit
* architectures is usually 64 bits so it would all fail horribly on huge
* volumes. I guess we need to define our own encode and decode fh functions
* that store 64-bit inode numbers at some point but for now we will ignore the
* problem...
*
* We also use the default ->get_name() helper (used by ->decode_fh() via
* fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs
* independent.
*
* The default ->get_parent() just returns -EACCES so we have to provide our
* own and the default ->get_dentry() is incompatible with NTFS due to not
* allowing the inode number 0 which is used in NTFS for the system file $MFT
* and due to using iget() whereas NTFS needs ntfs_iget().
*/
struct export_operations ntfs_export_ops = {
.get_parent = ntfs_get_parent, /* Find the parent of a given
directory. */
.get_dentry = ntfs_get_dentry, /* Find a dentry for the inode
given a file handle
sub-fragment. */
};
