linux/fs/ntfs/namei.c
Arjan van de Ven 92e1d5be91 [PATCH] mark struct inode_operations const 2
Many struct inode_operations in the kernel can be "const".  Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data.  In addition it'll catch accidental writes at compile time to
these shared resources.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:46 -08:00

525 lines
18 KiB
C

/*
* 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) {
if (uname_len != -ENAMETOOLONG)
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.
*/
const 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. */
};