Commit 2e08edc5 authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs dcache updates from Al Viro:
 "Part of this is what the trylock loop elimination series has turned
  into, part making d_move() preserve the parent (and thus the path) of
  victim, plus some general cleanups"

* 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (22 commits)
  d_genocide: move export to definition
  fold dentry_lock_for_move() into its sole caller and clean it up
  make non-exchanging __d_move() copy ->d_parent rather than swap them
  oprofilefs: don't oops on allocation failure
  lustre: get rid of pointless casts to struct dentry *
  debugfs_lookup(): switch to lookup_one_len_unlocked()
  fold lookup_real() into __lookup_hash()
  take out orphan externs (empty_string/slash_string)
  split d_path() and friends into a separate file
  dcache.c: trim includes
  fs/dcache: Avoid a try_lock loop in shrink_dentry_list()
  get rid of trylock loop around dentry_kill()
  handle move to LRU in retain_dentry()
  dput(): consolidate the "do we need to retain it?" into an inlined helper
  split the slow part of lock_parent() off
  now lock_parent() can't run into killed dentry
  get rid of trylock loop in locking dentries on shrink list
  d_delete(): get rid of trylock loop
  fs/dcache: Move dentry_kill() below lock_parent()
  fs/dcache: Remove stale comment from dentry_kill()
  ...
parents 17dec0a9 04bbc979
...@@ -138,6 +138,9 @@ static int __oprofilefs_create_file(struct dentry *root, char const *name, ...@@ -138,6 +138,9 @@ static int __oprofilefs_create_file(struct dentry *root, char const *name,
struct dentry *dentry; struct dentry *dentry;
struct inode *inode; struct inode *inode;
if (!root)
return -ENOMEM;
inode_lock(d_inode(root)); inode_lock(d_inode(root));
dentry = d_alloc_name(root, name); dentry = d_alloc_name(root, name);
if (!dentry) { if (!dentry) {
......
...@@ -90,7 +90,7 @@ static int ll_dcompare(const struct dentry *dentry, ...@@ -90,7 +90,7 @@ static int ll_dcompare(const struct dentry *dentry,
d_count(dentry)); d_count(dentry));
/* mountpoint is always valid */ /* mountpoint is always valid */
if (d_mountpoint((struct dentry *)dentry)) if (d_mountpoint(dentry))
return 0; return 0;
if (d_lustre_invalid(dentry)) if (d_lustre_invalid(dentry))
...@@ -111,7 +111,7 @@ static int ll_ddelete(const struct dentry *de) ...@@ -111,7 +111,7 @@ static int ll_ddelete(const struct dentry *de)
LASSERT(de); LASSERT(de);
CDEBUG(D_DENTRY, "%s dentry %pd (%p, parent %p, inode %p) %s%s\n", CDEBUG(D_DENTRY, "%s dentry %pd (%p, parent %p, inode %p) %s%s\n",
d_lustre_invalid((struct dentry *)de) ? "deleting" : "keeping", d_lustre_invalid(de) ? "deleting" : "keeping",
de, de, de->d_parent, d_inode(de), de, de, de->d_parent, d_inode(de),
d_unhashed(de) ? "" : "hashed,", d_unhashed(de) ? "" : "hashed,",
list_empty(&de->d_subdirs) ? "" : "subdirs"); list_empty(&de->d_subdirs) ? "" : "subdirs");
...@@ -119,7 +119,7 @@ static int ll_ddelete(const struct dentry *de) ...@@ -119,7 +119,7 @@ static int ll_ddelete(const struct dentry *de)
/* kernel >= 2.6.38 last refcount is decreased after this function. */ /* kernel >= 2.6.38 last refcount is decreased after this function. */
LASSERT(d_count(de) == 1); LASSERT(d_count(de) == 1);
if (d_lustre_invalid((struct dentry *)de)) if (d_lustre_invalid(de))
return 1; return 1;
return 0; return 0;
} }
......
...@@ -11,7 +11,7 @@ obj-y := open.o read_write.o file_table.o super.o \ ...@@ -11,7 +11,7 @@ obj-y := open.o read_write.o file_table.o super.o \
ioctl.o readdir.o select.o dcache.o inode.o \ ioctl.o readdir.o select.o dcache.o inode.o \
attr.o bad_inode.o file.o filesystems.o namespace.o \ attr.o bad_inode.o file.o filesystems.o namespace.o \
seq_file.o xattr.o libfs.o fs-writeback.o \ seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o splice.o sync.o utimes.o \ pnode.o splice.o sync.o utimes.o d_path.o \
stack.o fs_struct.o statfs.o fs_pin.o nsfs.o stack.o fs_struct.o statfs.o fs_pin.o nsfs.o
ifeq ($(CONFIG_BLOCK),y) ifeq ($(CONFIG_BLOCK),y)
......
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/syscalls.h>
#include <linux/export.h>
#include <linux/uaccess.h>
#include <linux/fs_struct.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/prefetch.h>
#include "mount.h"
static int prepend(char **buffer, int *buflen, const char *str, int namelen)
{
*buflen -= namelen;
if (*buflen < 0)
return -ENAMETOOLONG;
*buffer -= namelen;
memcpy(*buffer, str, namelen);
return 0;
}
/**
* prepend_name - prepend a pathname in front of current buffer pointer
* @buffer: buffer pointer
* @buflen: allocated length of the buffer
* @name: name string and length qstr structure
*
* With RCU path tracing, it may race with d_move(). Use READ_ONCE() to
* make sure that either the old or the new name pointer and length are
* fetched. However, there may be mismatch between length and pointer.
* The length cannot be trusted, we need to copy it byte-by-byte until
* the length is reached or a null byte is found. It also prepends "/" at
* the beginning of the name. The sequence number check at the caller will
* retry it again when a d_move() does happen. So any garbage in the buffer
* due to mismatched pointer and length will be discarded.
*
* Load acquire is needed to make sure that we see that terminating NUL.
*/
static int prepend_name(char **buffer, int *buflen, const struct qstr *name)
{
const char *dname = smp_load_acquire(&name->name); /* ^^^ */
u32 dlen = READ_ONCE(name->len);
char *p;
*buflen -= dlen + 1;
if (*buflen < 0)
return -ENAMETOOLONG;
p = *buffer -= dlen + 1;
*p++ = '/';
while (dlen--) {
char c = *dname++;
if (!c)
break;
*p++ = c;
}
return 0;
}
/**
* prepend_path - Prepend path string to a buffer
* @path: the dentry/vfsmount to report
* @root: root vfsmnt/dentry
* @buffer: pointer to the end of the buffer
* @buflen: pointer to buffer length
*
* The function will first try to write out the pathname without taking any
* lock other than the RCU read lock to make sure that dentries won't go away.
* It only checks the sequence number of the global rename_lock as any change
* in the dentry's d_seq will be preceded by changes in the rename_lock
* sequence number. If the sequence number had been changed, it will restart
* the whole pathname back-tracing sequence again by taking the rename_lock.
* In this case, there is no need to take the RCU read lock as the recursive
* parent pointer references will keep the dentry chain alive as long as no
* rename operation is performed.
*/
static int prepend_path(const struct path *path,
const struct path *root,
char **buffer, int *buflen)
{
struct dentry *dentry;
struct vfsmount *vfsmnt;
struct mount *mnt;
int error = 0;
unsigned seq, m_seq = 0;
char *bptr;
int blen;
rcu_read_lock();
restart_mnt:
read_seqbegin_or_lock(&mount_lock, &m_seq);
seq = 0;
rcu_read_lock();
restart:
bptr = *buffer;
blen = *buflen;
error = 0;
dentry = path->dentry;
vfsmnt = path->mnt;
mnt = real_mount(vfsmnt);
read_seqbegin_or_lock(&rename_lock, &seq);
while (dentry != root->dentry || vfsmnt != root->mnt) {
struct dentry * parent;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
struct mount *parent = READ_ONCE(mnt->mnt_parent);
/* Escaped? */
if (dentry != vfsmnt->mnt_root) {
bptr = *buffer;
blen = *buflen;
error = 3;
break;
}
/* Global root? */
if (mnt != parent) {
dentry = READ_ONCE(mnt->mnt_mountpoint);
mnt = parent;
vfsmnt = &mnt->mnt;
continue;
}
if (!error)
error = is_mounted(vfsmnt) ? 1 : 2;
break;
}
parent = dentry->d_parent;
prefetch(parent);
error = prepend_name(&bptr, &blen, &dentry->d_name);
if (error)
break;
dentry = parent;
}
if (!(seq & 1))
rcu_read_unlock();
if (need_seqretry(&rename_lock, seq)) {
seq = 1;
goto restart;
}
done_seqretry(&rename_lock, seq);
if (!(m_seq & 1))
rcu_read_unlock();
if (need_seqretry(&mount_lock, m_seq)) {
m_seq = 1;
goto restart_mnt;
}
done_seqretry(&mount_lock, m_seq);
if (error >= 0 && bptr == *buffer) {
if (--blen < 0)
error = -ENAMETOOLONG;
else
*--bptr = '/';
}
*buffer = bptr;
*buflen = blen;
return error;
}
/**
* __d_path - return the path of a dentry
* @path: the dentry/vfsmount to report
* @root: root vfsmnt/dentry
* @buf: buffer to return value in
* @buflen: buffer length
*
* Convert a dentry into an ASCII path name.
*
* Returns a pointer into the buffer or an error code if the
* path was too long.
*
* "buflen" should be positive.
*
* If the path is not reachable from the supplied root, return %NULL.
*/
char *__d_path(const struct path *path,
const struct path *root,
char *buf, int buflen)
{
char *res = buf + buflen;
int error;
prepend(&res, &buflen, "\0", 1);
error = prepend_path(path, root, &res, &buflen);
if (error < 0)
return ERR_PTR(error);
if (error > 0)
return NULL;
return res;
}
char *d_absolute_path(const struct path *path,
char *buf, int buflen)
{
struct path root = {};
char *res = buf + buflen;
int error;
prepend(&res, &buflen, "\0", 1);
error = prepend_path(path, &root, &res, &buflen);
if (error > 1)
error = -EINVAL;
if (error < 0)
return ERR_PTR(error);
return res;
}
/*
* same as __d_path but appends "(deleted)" for unlinked files.
*/
static int path_with_deleted(const struct path *path,
const struct path *root,
char **buf, int *buflen)
{
prepend(buf, buflen, "\0", 1);
if (d_unlinked(path->dentry)) {
int error = prepend(buf, buflen, " (deleted)", 10);
if (error)
return error;
}
return prepend_path(path, root, buf, buflen);
}
static int prepend_unreachable(char **buffer, int *buflen)
{
return prepend(buffer, buflen, "(unreachable)", 13);
}
static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
{
unsigned seq;
do {
seq = read_seqcount_begin(&fs->seq);
*root = fs->root;
} while (read_seqcount_retry(&fs->seq, seq));
}
/**
* d_path - return the path of a dentry
* @path: path to report
* @buf: buffer to return value in
* @buflen: buffer length
*
* Convert a dentry into an ASCII path name. If the entry has been deleted
* the string " (deleted)" is appended. Note that this is ambiguous.
*
* Returns a pointer into the buffer or an error code if the path was
* too long. Note: Callers should use the returned pointer, not the passed
* in buffer, to use the name! The implementation often starts at an offset
* into the buffer, and may leave 0 bytes at the start.
*
* "buflen" should be positive.
*/
char *d_path(const struct path *path, char *buf, int buflen)
{
char *res = buf + buflen;
struct path root;
int error;
/*
* We have various synthetic filesystems that never get mounted. On
* these filesystems dentries are never used for lookup purposes, and
* thus don't need to be hashed. They also don't need a name until a
* user wants to identify the object in /proc/pid/fd/. The little hack
* below allows us to generate a name for these objects on demand:
*
* Some pseudo inodes are mountable. When they are mounted
* path->dentry == path->mnt->mnt_root. In that case don't call d_dname
* and instead have d_path return the mounted path.
*/
if (path->dentry->d_op && path->dentry->d_op->d_dname &&
(!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root))
return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
rcu_read_lock();
get_fs_root_rcu(current->fs, &root);
error = path_with_deleted(path, &root, &res, &buflen);
rcu_read_unlock();
if (error < 0)
res = ERR_PTR(error);
return res;
}
EXPORT_SYMBOL(d_path);
/*
* Helper function for dentry_operations.d_dname() members
*/
char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
const char *fmt, ...)
{
va_list args;
char temp[64];
int sz;
va_start(args, fmt);
sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
va_end(args);
if (sz > sizeof(temp) || sz > buflen)
return ERR_PTR(-ENAMETOOLONG);
buffer += buflen - sz;
return memcpy(buffer, temp, sz);
}
char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
{
char *end = buffer + buflen;
/* these dentries are never renamed, so d_lock is not needed */
if (prepend(&end, &buflen, " (deleted)", 11) ||
prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) ||
prepend(&end, &buflen, "/", 1))
end = ERR_PTR(-ENAMETOOLONG);
return end;
}
EXPORT_SYMBOL(simple_dname);
/*
* Write full pathname from the root of the filesystem into the buffer.
*/
static char *__dentry_path(struct dentry *d, char *buf, int buflen)
{
struct dentry *dentry;
char *end, *retval;
int len, seq = 0;
int error = 0;
if (buflen < 2)
goto Elong;
rcu_read_lock();
restart:
dentry = d;
end = buf + buflen;
len = buflen;
prepend(&end, &len, "\0", 1);
/* Get '/' right */
retval = end-1;
*retval = '/';
read_seqbegin_or_lock(&rename_lock, &seq);
while (!IS_ROOT(dentry)) {
struct dentry *parent = dentry->d_parent;
prefetch(parent);
error = prepend_name(&end, &len, &dentry->d_name);
if (error)
break;
retval = end;
dentry = parent;
}
if (!(seq & 1))
rcu_read_unlock();
if (need_seqretry(&rename_lock, seq)) {
seq = 1;
goto restart;
}
done_seqretry(&rename_lock, seq);
if (error)
goto Elong;
return retval;
Elong:
return ERR_PTR(-ENAMETOOLONG);
}
char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
{
return __dentry_path(dentry, buf, buflen);
}
EXPORT_SYMBOL(dentry_path_raw);
char *dentry_path(struct dentry *dentry, char *buf, int buflen)
{
char *p = NULL;
char *retval;
if (d_unlinked(dentry)) {
p = buf + buflen;
if (prepend(&p, &buflen, "//deleted", 10) != 0)
goto Elong;
buflen++;
}
retval = __dentry_path(dentry, buf, buflen);
if (!IS_ERR(retval) && p)
*p = '/'; /* restore '/' overriden with '\0' */
return retval;
Elong:
return ERR_PTR(-ENAMETOOLONG);
}
static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root,
struct path *pwd)
{
unsigned seq;
do {
seq = read_seqcount_begin(&fs->seq);
*root = fs->root;
*pwd = fs->pwd;
} while (read_seqcount_retry(&fs->seq, seq));
}
/*
* NOTE! The user-level library version returns a
* character pointer. The kernel system call just
* returns the length of the buffer filled (which
* includes the ending '\0' character), or a negative
* error value. So libc would do something like
*
* char *getcwd(char * buf, size_t size)
* {
* int retval;
*
* retval = sys_getcwd(buf, size);
* if (retval >= 0)
* return buf;
* errno = -retval;
* return NULL;
* }
*/
SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
{
int error;
struct path pwd, root;
char *page = __getname();
if (!page)
return -ENOMEM;
rcu_read_lock();
get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
error = -ENOENT;
if (!d_unlinked(pwd.dentry)) {
unsigned long len;
char *cwd = page + PATH_MAX;
int buflen = PATH_MAX;
prepend(&cwd, &buflen, "\0", 1);
error = prepend_path(&pwd, &root, &cwd, &buflen);
rcu_read_unlock();
if (error < 0)
goto out;
/* Unreachable from current root */
if (error > 0) {
error = prepend_unreachable(&cwd, &buflen);
if (error)
goto out;
}
error = -ERANGE;
len = PATH_MAX + page - cwd;
if (len <= size) {
error = len;
if (copy_to_user(buf, cwd, len))
error = -EFAULT;
}
} else {
rcu_read_unlock();
}
out:
__putname(page);
return error;
}
...@@ -14,7 +14,7 @@ ...@@ -14,7 +14,7 @@
* the dcache entry is deleted or garbage collected. * the dcache entry is deleted or garbage collected.
*/ */
#include <linux/syscalls.h> #include <linux/ratelimit.h>
#include <linux/string.h> #include <linux/string.h>
#include <linux/mm.h> #include <linux/mm.h>
#include <linux/fs.h> #include <linux/fs.h>
...@@ -24,18 +24,11 @@ ...@@ -24,18 +24,11 @@
#include <linux/hash.h> #include <linux/hash.h>
#include <linux/cache.h> #include <linux/cache.h>
#include <linux/export.h> #include <linux/export.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/security.h> #include <linux/security.h>
#include <linux/seqlock.h> #include <linux/seqlock.h>
#include <linux/swap.h>
#include <linux/bootmem.h> #include <linux/bootmem.h>
#include <linux/fs_struct.h>
#include <linux/bit_spinlock.h> #include <linux/bit_spinlock.h>
#include <linux/rculist_bl.h> #include <linux/rculist_bl.h>
#include <linux/prefetch.h>
#include <linux/ratelimit.h>
#include <linux/list_lru.h> #include <linux/list_lru.h>
#include "internal.h" #include "internal.h"
#include "mount.h" #include "mount.h"
...@@ -74,9 +67,7 @@ ...@@ -74,9 +67,7 @@
* dentry->d_lock * dentry->d_lock
* *
* If no ancestor relationship: * If no ancestor relationship:
* if (dentry1 < dentry2) * arbitrary, since it's serialized on rename_lock
* dentry1->d_lock
* dentry2->d_lock
*/ */
int sysctl_vfs_cache_pressure __read_mostly = 100; int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
...@@ -440,17 +431,6 @@ static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry, ...@@ -440,17 +431,6 @@ static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry,
list_lru_isolate_move(lru, &dentry->d_lru, list); list_lru_isolate_move(lru, &dentry->d_lru, list);
} }
/*
* dentry_lru_(add|del)_list) must be called with d_lock held.
*/
static void dentry_lru_add(struct dentry *dentry)
{
if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
d_lru_add(dentry);
else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
dentry->d_flags |= DCACHE_REFERENCED;
}
/** /**
* d_drop - drop a dentry * d_drop - drop a dentry
* @dentry: dentry to drop * @dentry: dentry to drop
...@@ -470,7 +450,6 @@ static void dentry_lru_add(struct dentry *dentry) ...@@ -470,7 +450,6 @@ static void dentry_lru_add(struct dentry *dentry)
*/ */
static void ___d_drop(struct dentry *dentry) static void ___d_drop(struct dentry *dentry)
{ {
if (!d_unhashed(dentry)) {
struct hlist_bl_head *b; struct hlist_bl_head *b;
/* /*
* Hashed dentries are normally on the dentry hashtable, * Hashed dentries are normally on the dentry hashtable,
...@@ -485,15 +464,15 @@ static void ___d_drop(struct dentry *dentry) ...@@ -485,15 +464,15 @@ static void ___d_drop(struct dentry *dentry)
hlist_bl_lock(b); hlist_bl_lock(b);
__hlist_bl_del(&dentry->d_hash); __hlist_bl_del(&dentry->d_hash);
hlist_bl_unlock(b); hlist_bl_unlock(b);
/* After this call, in-progress rcu-walk path lookup will fail. */
write_seqcount_invalidate(&dentry->d_seq);
}
} }
void __d_drop(struct dentry *dentry) void __d_drop(struct dentry *dentry)
{ {
if (!d_unhashed(dentry)) {
___d_drop(dentry); ___d_drop(dentry);
dentry->d_hash.pprev = NULL; dentry->d_hash.pprev = NULL;
write_seqcount_invalidate(&dentry->d_seq);
}
} }
EXPORT_SYMBOL(__d_drop); EXPORT_SYMBOL(__d_drop);
...@@ -589,10 +568,71 @@ static void __dentry_kill(struct dentry *dentry) ...@@ -589,10 +568,71 @@ static void __dentry_kill(struct dentry *dentry)
dentry_free(dentry); dentry_free(dentry);
} }
static struct dentry *__lock_parent(struct dentry *dentry)
{
struct dentry *parent;
rcu_read_lock();
spin_unlock(&dentry->d_lock);
again:
parent = READ_ONCE(dentry->d_parent);
spin_lock(&parent->d_lock);
/*
* We can't blindly lock dentry until we are sure
* that we won't violate the locking order.
* Any changes of dentry->d_parent must have
* been done with parent->d_lock held, so
* spin_lock() above is enough of a barrier
* for checking if it's still our child.
*/
if (unlikely(parent != dentry->d_parent)) {
spin_unlock(&parent->d_lock);
goto again;
}
rcu_read_unlock();
if (parent != dentry)
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
else
parent = NULL;
return parent;
}
static inline struct dentry *lock_parent(struct dentry *dentry)
{
struct dentry *parent = dentry->d_parent;
if (IS_ROOT(dentry))
return NULL;
if (likely(spin_trylock(&parent->d_lock)))
return parent;
return __lock_parent(dentry);
}
static inline bool retain_dentry(struct dentry *dentry)
{
WARN_ON(d_in_lookup(dentry));
/* Unreachable? Get rid of it */
if (unlikely(d_unhashed(dentry)))
return false;
if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
return false;
if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
if (dentry->d_op->d_delete(dentry))
return false;
}
/* retain; LRU fodder */
dentry->d_lockref.count--;
if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
d_lru_add(dentry);
else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
dentry->d_flags |= DCACHE_REFERENCED;
return true;
}
/* /*
* Finish off a dentry we've decided to kill. * Finish off a dentry we've decided to kill.
* dentry->d_lock must be held, returns with it unlocked. * dentry->d_lock must be held, returns with it unlocked.
* If ref is non-zero, then decrement the refcount too.
* Returns dentry requiring refcount drop, or NULL if we're done. * Returns dentry requiring refcount drop, or NULL if we're done.
*/ */
static struct dentry *dentry_kill(struct dentry *dentry) static struct dentry *dentry_kill(struct dentry *dentry)
...@@ -602,62 +642,43 @@ static struct dentry *dentry_kill(struct dentry *dentry) ...@@ -602,62 +642,43 @@ static struct dentry *dentry_kill(struct dentry *dentry)
struct dentry *parent = NULL; struct dentry *parent = NULL;
if (inode && unlikely(!spin_trylock(&inode->i_lock))) if (inode && unlikely(!spin_trylock(&inode->i_lock)))
goto failed; goto slow_positive;
if (!IS_ROOT(dentry)) { if (!IS_ROOT(dentry)) {
parent = dentry->d_parent; parent = dentry->d_parent;
if (unlikely(!spin_trylock(&parent->d_lock))) { if (unlikely(!spin_trylock(&parent->d_lock))) {
if (inode) parent = __lock_parent(dentry);
spin_unlock(&inode->i_lock); if (likely(inode || !dentry->d_inode))
goto failed; goto got_locks;
/* negative that became positive */
if (parent)
spin_unlock(&parent->d_lock);
inode = dentry->d_inode;
goto slow_positive;
} }
} }
__dentry_kill(dentry); __dentry_kill(dentry);
return parent; return parent;
failed: slow_positive:
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
return dentry; /* try again with same dentry */ spin_lock(&inode->i_lock);
} spin_lock(&dentry->d_lock);
parent = lock_parent(dentry);
static inline struct dentry *lock_parent(struct dentry *dentry) got_locks:
{ if (unlikely(dentry->d_lockref.count != 1)) {
struct dentry *parent = dentry->d_parent; dentry->d_lockref.count--;
if (IS_ROOT(dentry)) } else if (likely(!retain_dentry(dentry))) {
return NULL; __dentry_kill(dentry);
if (unlikely(dentry->d_lockref.count < 0))
return NULL;
if (likely(spin_trylock(&parent->d_lock)))
return parent; return parent;
rcu_read_lock();
spin_unlock(&dentry->d_lock);
again:
parent = READ_ONCE(dentry->d_parent);
spin_lock(&parent->d_lock);
/*
* We can't blindly lock dentry until we are sure
* that we won't violate the locking order.
* Any changes of dentry->d_parent must have
* been done with parent->d_lock held, so
* spin_lock() above is enough of a barrier
* for checking if it's still our child.
*/
if (unlikely(parent != dentry->d_parent)) {
spin_unlock(&parent->d_lock);
goto again;
} }
if (parent != dentry) { /* we are keeping it, after all */
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); if (inode)
if (unlikely(dentry->d_lockref.count < 0)) { spin_unlock(&inode->i_lock);
if (parent)
spin_unlock(&parent->d_lock); spin_unlock(&parent->d_lock);
parent = NULL; spin_unlock(&dentry->d_lock);
} return NULL;
} else {
parent = NULL;
}
rcu_read_unlock();
return parent;
} }
/* /*
...@@ -807,27 +828,11 @@ void dput(struct dentry *dentry) ...@@ -807,27 +828,11 @@ void dput(struct dentry *dentry)
/* Slow case: now with the dentry lock held */ /* Slow case: now with the dentry lock held */
rcu_read_unlock(); rcu_read_unlock();
WARN_ON(d_in_lookup(dentry)); if (likely(retain_dentry(dentry))) {
/* Unreachable? Get rid of it */
if (unlikely(d_unhashed(dentry)))
goto kill_it;
if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
goto kill_it;
if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
if (dentry->d_op->d_delete(dentry))
goto kill_it;
}
dentry_lru_add(dentry);
dentry->d_lockref.count--;
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
return; return;
}
kill_it:
dentry = dentry_kill(dentry); dentry = dentry_kill(dentry);
if (dentry) { if (dentry) {
cond_resched(); cond_resched();
...@@ -976,56 +981,83 @@ void d_prune_aliases(struct inode *inode) ...@@ -976,56 +981,83 @@ void d_prune_aliases(struct inode *inode)
} }
EXPORT_SYMBOL(d_prune_aliases); EXPORT_SYMBOL(d_prune_aliases);
static void shrink_dentry_list(struct list_head *list) /*
* Lock a dentry from shrink list.
* Called under rcu_read_lock() and dentry->d_lock; the former
* guarantees that nothing we access will be freed under us.
* Note that dentry is *not* protected from concurrent dentry_kill(),
* d_delete(), etc.
*
* Return false if dentry has been disrupted or grabbed, leaving
* the caller to kick it off-list. Otherwise, return true and have
* that dentry's inode and parent both locked.
*/
static bool shrink_lock_dentry(struct dentry *dentry)
{ {
struct dentry *dentry, *parent;
while (!list_empty(list)) {
struct inode *inode; struct inode *inode;
dentry = list_entry(list->prev, struct dentry, d_lru); struct dentry *parent;
spin_lock(&dentry->d_lock);
parent = lock_parent(dentry);
/* if (dentry->d_lockref.count)
* The dispose list is isolated and dentries are not accounted return false;
* to the LRU here, so we can simply remove it from the list
* here regardless of whether it is referenced or not.
*/
d_shrink_del(dentry);
/* inode = dentry->d_inode;
* We found an inuse dentry which was not removed from if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
* the LRU because of laziness during lookup. Do not free it.
*/
if (dentry->d_lockref.count > 0) {
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
if (parent) spin_lock(&inode->i_lock);
spin_unlock(&parent->d_lock); spin_lock(&dentry->d_lock);
continue; if (unlikely(dentry->d_lockref.count))
goto out;
/* changed inode means that somebody had grabbed it */
if (unlikely(inode != dentry->d_inode))
goto out;
} }
parent = dentry->d_parent;
if (IS_ROOT(dentry) || likely(spin_trylock(&parent->d_lock)))
return true;
if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
bool can_free = dentry->d_flags & DCACHE_MAY_FREE;
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
if (parent) spin_lock(&parent->d_lock);
if (unlikely(parent != dentry->d_parent)) {
spin_unlock(&parent->d_lock); spin_unlock(&parent->d_lock);
if (can_free) spin_lock(&dentry->d_lock);
dentry_free(dentry); goto out;
continue;
} }
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
if (likely(!dentry->d_lockref.count))
return true;
spin_unlock(&parent->d_lock);
out:
if (inode)
spin_unlock(&inode->i_lock);
return false;
}
inode = dentry->d_inode; static void shrink_dentry_list(struct list_head *list)
if (inode && unlikely(!spin_trylock(&inode->i_lock))) { {
d_shrink_add(dentry, list); while (!list_empty(list)) {
struct dentry *dentry, *parent;
dentry = list_entry(list->prev, struct dentry, d_lru);
spin_lock(&dentry->d_lock);
rcu_read_lock();
if (!shrink_lock_dentry(dentry)) {
bool can_free = false;
rcu_read_unlock();
d_shrink_del(dentry);
if (dentry->d_lockref.count < 0)
can_free = dentry->d_flags & DCACHE_MAY_FREE;
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
if (parent) if (can_free)
spin_unlock(&parent->d_lock); dentry_free(dentry);
continue; continue;
} }
rcu_read_unlock();
d_shrink_del(dentry);
parent = dentry->d_parent;
__dentry_kill(dentry); __dentry_kill(dentry);
if (parent == dentry)
continue;
/* /*
* We need to prune ancestors too. This is necessary to prevent * We need to prune ancestors too. This is necessary to prevent
* quadratic behavior of shrink_dcache_parent(), but is also * quadratic behavior of shrink_dcache_parent(), but is also
...@@ -1033,26 +1065,8 @@ static void shrink_dentry_list(struct list_head *list) ...@@ -1033,26 +1065,8 @@ static void shrink_dentry_list(struct list_head *list)
* fragmentation. * fragmentation.
*/ */
dentry = parent; dentry = parent;
while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { while (dentry && !lockref_put_or_lock(&dentry->d_lockref))
parent = lock_parent(dentry); dentry = dentry_kill(dentry);
if (dentry->d_lockref.count != 1) {
dentry->d_lockref.count--;
spin_unlock(&dentry->d_lock);
if (parent)
spin_unlock(&parent->d_lock);
break;
}
inode = dentry->d_inode; /* can't be NULL */
if (unlikely(!spin_trylock(&inode->i_lock))) {
spin_unlock(&dentry->d_lock);
if (parent)
spin_unlock(&parent->d_lock);
cpu_relax();
continue;
}
__dentry_kill(dentry);
dentry = parent;
}
} }
} }
...@@ -2379,32 +2393,22 @@ EXPORT_SYMBOL(d_hash_and_lookup); ...@@ -2379,32 +2393,22 @@ EXPORT_SYMBOL(d_hash_and_lookup);
void d_delete(struct dentry * dentry) void d_delete(struct dentry * dentry)
{ {
struct inode *inode; struct inode *inode = dentry->d_inode;
int isdir = 0; int isdir = d_is_dir(dentry);
spin_lock(&inode->i_lock);
spin_lock(&dentry->d_lock);
/* /*
* Are we the only user? * Are we the only user?
*/ */
again:
spin_lock(&dentry->d_lock);
inode = dentry->d_inode;
isdir = S_ISDIR(inode->i_mode);
if (dentry->d_lockref.count == 1) { if (dentry->d_lockref.count == 1) {
if (!spin_trylock(&inode->i_lock)) {
spin_unlock(&dentry->d_lock);
cpu_relax();
goto again;
}
dentry->d_flags &= ~DCACHE_CANT_MOUNT; dentry->d_flags &= ~DCACHE_CANT_MOUNT;
dentry_unlink_inode(dentry); dentry_unlink_inode(dentry);
fsnotify_nameremove(dentry, isdir); } else {
return;
}
if (!d_unhashed(dentry))
__d_drop(dentry); __d_drop(dentry);
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
spin_unlock(&inode->i_lock);
}
fsnotify_nameremove(dentry, isdir); fsnotify_nameremove(dentry, isdir);
} }
EXPORT_SYMBOL(d_delete); EXPORT_SYMBOL(d_delete);
...@@ -2769,57 +2773,6 @@ static void copy_name(struct dentry *dentry, struct dentry *target) ...@@ -2769,57 +2773,6 @@ static void copy_name(struct dentry *dentry, struct dentry *target)
kfree_rcu(old_name, u.head); kfree_rcu(old_name, u.head);
} }
static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
{
/*
* XXXX: do we really need to take target->d_lock?
*/
if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
spin_lock(&target->d_parent->d_lock);
else {
if (d_ancestor(dentry->d_parent, target->d_parent)) {
spin_lock(&dentry->d_parent->d_lock);
spin_lock_nested(&target->d_parent->d_lock,
DENTRY_D_LOCK_NESTED);
} else {
spin_lock(&target->d_parent->d_lock);
spin_lock_nested(&dentry->d_parent->d_lock,
DENTRY_D_LOCK_NESTED);
}
}
if (target < dentry) {
spin_lock_nested(&target->d_lock, 2);
spin_lock_nested(&dentry->d_lock, 3);
} else {
spin_lock_nested(&dentry->d_lock, 2);
spin_lock_nested(&target->d_lock, 3);
}
}
static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
{
if (target->d_parent != dentry->d_parent)
spin_unlock(&dentry->d_parent->d_lock);
if (target->d_parent != target)
spin_unlock(&target->d_parent->d_lock);
spin_unlock(&target->d_lock);
spin_unlock(&dentry->d_lock);
}
/*
* When switching names, the actual string doesn't strictly have to
* be preserved in the target - because we're dropping the target
* anyway. As such, we can just do a simple memcpy() to copy over
* the new name before we switch, unless we are going to rehash
* it. Note that if we *do* unhash the target, we are not allowed
* to rehash it without giving it a new name/hash key - whether
* we swap or overwrite the names here, resulting name won't match
* the reality in filesystem; it's only there for d_path() purposes.
* Note that all of this is happening under rename_lock, so the
* any hash lookup seeing it in the middle of manipulations will
* be discarded anyway. So we do not care what happens to the hash
* key in that case.
*/
/* /*
* __d_move - move a dentry * __d_move - move a dentry
* @dentry: entry to move * @dentry: entry to move
...@@ -2834,15 +2787,34 @@ static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target) ...@@ -2834,15 +2787,34 @@ static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
static void __d_move(struct dentry *dentry, struct dentry *target, static void __d_move(struct dentry *dentry, struct dentry *target,
bool exchange) bool exchange)
{ {
struct dentry *old_parent, *p;
struct inode *dir = NULL; struct inode *dir = NULL;
unsigned n; unsigned n;
if (!dentry->d_inode)
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
BUG_ON(d_ancestor(dentry, target)); WARN_ON(!dentry->d_inode);
if (WARN_ON(dentry == target))
return;
BUG_ON(d_ancestor(target, dentry)); BUG_ON(d_ancestor(target, dentry));
old_parent = dentry->d_parent;
p = d_ancestor(old_parent, target);
if (IS_ROOT(dentry)) {
BUG_ON(p);
spin_lock(&target->d_parent->d_lock);
} else if (!p) {
/* target is not a descendent of dentry->d_parent */
spin_lock(&target->d_parent->d_lock);
spin_lock_nested(&old_parent->d_lock, DENTRY_D_LOCK_NESTED);
} else {
BUG_ON(p == dentry);
spin_lock(&old_parent->d_lock);
if (p != target)
spin_lock_nested(&target->d_parent->d_lock,
DENTRY_D_LOCK_NESTED);
}
spin_lock_nested(&dentry->d_lock, 2);
spin_lock_nested(&target->d_lock, 3);
dentry_lock_for_move(dentry, target);
if (unlikely(d_in_lookup(target))) { if (unlikely(d_in_lookup(target))) {
dir = target->d_parent->d_inode; dir = target->d_parent->d_inode;
n = start_dir_add(dir); n = start_dir_add(dir);
...@@ -2853,47 +2825,44 @@ static void __d_move(struct dentry *dentry, struct dentry *target, ...@@ -2853,47 +2825,44 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
/* unhash both */ /* unhash both */
/* ___d_drop does write_seqcount_barrier, but they're OK to nest. */ if (!d_unhashed(dentry))
___d_drop(dentry); ___d_drop(dentry);
if (!d_unhashed(target))
___d_drop(target); ___d_drop(target);
/* Switch the names.. */ /* ... and switch them in the tree */
if (exchange) dentry->d_parent = target->d_parent;
swap_names(dentry, target); if (!exchange) {
else
copy_name(dentry, target); copy_name(dentry, target);
/* rehash in new place(s) */
__d_rehash(dentry);
if (exchange)
__d_rehash(target);
else
target->d_hash.pprev = NULL; target->d_hash.pprev = NULL;
dentry->d_parent->d_lockref.count++;
/* ... and switch them in the tree */ if (dentry == old_parent)
if (IS_ROOT(dentry)) {
/* splicing a tree */
dentry->d_flags |= DCACHE_RCUACCESS; dentry->d_flags |= DCACHE_RCUACCESS;
dentry->d_parent = target->d_parent; else
target->d_parent = target; WARN_ON(!--old_parent->d_lockref.count);
list_del_init(&target->d_child);
list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
} else { } else {
/* swapping two dentries */ target->d_parent = old_parent;
swap(dentry->d_parent, target->d_parent); swap_names(dentry, target);
list_move(&target->d_child, &target->d_parent->d_subdirs); list_move(&target->d_child, &target->d_parent->d_subdirs);
list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); __d_rehash(target);
if (exchange)
fsnotify_update_flags(target); fsnotify_update_flags(target);
fsnotify_update_flags(dentry);
} }
list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
__d_rehash(dentry);
fsnotify_update_flags(dentry);
write_seqcount_end(&target->d_seq); write_seqcount_end(&target->d_seq);
write_seqcount_end(&dentry->d_seq); write_seqcount_end(&dentry->d_seq);
if (dir) if (dir)
end_dir_add(dir, n); end_dir_add(dir, n);
dentry_unlock_for_move(dentry, target);
if (dentry->d_parent != old_parent)
spin_unlock(&dentry->d_parent->d_lock);
if (dentry != old_parent)
spin_unlock(&old_parent->d_lock);
spin_unlock(&target->d_lock);
spin_unlock(&dentry->d_lock);
} }
/* /*
...@@ -3041,12 +3010,14 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) ...@@ -3041,12 +3010,14 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
inode->i_sb->s_type->name, inode->i_sb->s_type->name,
inode->i_sb->s_id); inode->i_sb->s_id);
} else if (!IS_ROOT(new)) { } else if (!IS_ROOT(new)) {
struct dentry *old_parent = dget(new->d_parent);
int err = __d_unalias(inode, dentry, new); int err = __d_unalias(inode, dentry, new);
write_sequnlock(&rename_lock); write_sequnlock(&rename_lock);
if (err) { if (err) {
dput(new); dput(new);
new = ERR_PTR(err); new = ERR_PTR(err);
} }
dput(old_parent);
} else { } else {
__d_move(new, dentry, false); __d_move(new, dentry, false);
write_sequnlock(&rename_lock); write_sequnlock(&rename_lock);
...@@ -3061,467 +3032,6 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) ...@@ -3061,467 +3032,6 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
} }
EXPORT_SYMBOL(d_splice_alias); EXPORT_SYMBOL(d_splice_alias);
static int prepend(char **buffer, int *buflen, const char *str, int namelen)
{
*buflen -= namelen;
if (*buflen < 0)
return -ENAMETOOLONG;
*buffer -= namelen;
memcpy(*buffer, str, namelen);
return 0;
}
/**
* prepend_name - prepend a pathname in front of current buffer pointer
* @buffer: buffer pointer
* @buflen: allocated length of the buffer
* @name: name string and length qstr structure
*
* With RCU path tracing, it may race with d_move(). Use READ_ONCE() to
* make sure that either the old or the new name pointer and length are
* fetched. However, there may be mismatch between length and pointer.
* The length cannot be trusted, we need to copy it byte-by-byte until
* the length is reached or a null byte is found. It also prepends "/" at
* the beginning of the name. The sequence number check at the caller will
* retry it again when a d_move() does happen. So any garbage in the buffer
* due to mismatched pointer and length will be discarded.
*
* Load acquire is needed to make sure that we see that terminating NUL.
*/
static int prepend_name(char **buffer, int *buflen, const struct qstr *name)
{
const char *dname = smp_load_acquire(&name->name); /* ^^^ */
u32 dlen = READ_ONCE(name->len);
char *p;
*buflen -= dlen + 1;
if (*buflen < 0)
return -ENAMETOOLONG;
p = *buffer -= dlen + 1;
*p++ = '/';
while (dlen--) {
char c = *dname++;
if (!c)
break;
*p++ = c;
}
return 0;
}
/**
* prepend_path - Prepend path string to a buffer
* @path: the dentry/vfsmount to report
* @root: root vfsmnt/dentry
* @buffer: pointer to the end of the buffer
* @buflen: pointer to buffer length
*
* The function will first try to write out the pathname without taking any
* lock other than the RCU read lock to make sure that dentries won't go away.
* It only checks the sequence number of the global rename_lock as any change
* in the dentry's d_seq will be preceded by changes in the rename_lock
* sequence number. If the sequence number had been changed, it will restart
* the whole pathname back-tracing sequence again by taking the rename_lock.
* In this case, there is no need to take the RCU read lock as the recursive
* parent pointer references will keep the dentry chain alive as long as no
* rename operation is performed.
*/
static int prepend_path(const struct path *path,
const struct path *root,
char **buffer, int *buflen)
{
struct dentry *dentry;
struct vfsmount *vfsmnt;
struct mount *mnt;
int error = 0;
unsigned seq, m_seq = 0;
char *bptr;
int blen;
rcu_read_lock();
restart_mnt:
read_seqbegin_or_lock(&mount_lock, &m_seq);
seq = 0;
rcu_read_lock();
restart:
bptr = *buffer;
blen = *buflen;
error = 0;
dentry = path->dentry;
vfsmnt = path->mnt;
mnt = real_mount(vfsmnt);
read_seqbegin_or_lock(&rename_lock, &seq);
while (dentry != root->dentry || vfsmnt != root->mnt) {
struct dentry * parent;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
struct mount *parent = READ_ONCE(mnt->mnt_parent);
/* Escaped? */
if (dentry != vfsmnt->mnt_root) {
bptr = *buffer;
blen = *buflen;
error = 3;
break;
}
/* Global root? */
if (mnt != parent) {
dentry = READ_ONCE(mnt->mnt_mountpoint);
mnt = parent;
vfsmnt = &mnt->mnt;
continue;
}
if (!error)
error = is_mounted(vfsmnt) ? 1 : 2;
break;
}
parent = dentry->d_parent;
prefetch(parent);
error = prepend_name(&bptr, &blen, &dentry->d_name);
if (error)
break;
dentry = parent;
}
if (!(seq & 1))
rcu_read_unlock();
if (need_seqretry(&rename_lock, seq)) {
seq = 1;
goto restart;
}
done_seqretry(&rename_lock, seq);
if (!(m_seq & 1))
rcu_read_unlock();
if (need_seqretry(&mount_lock, m_seq)) {
m_seq = 1;
goto restart_mnt;
}
done_seqretry(&mount_lock, m_seq);
if (error >= 0 && bptr == *buffer) {
if (--blen < 0)
error = -ENAMETOOLONG;
else
*--bptr = '/';
}
*buffer = bptr;
*buflen = blen;
return error;
}
/**
* __d_path - return the path of a dentry
* @path: the dentry/vfsmount to report
* @root: root vfsmnt/dentry
* @buf: buffer to return value in
* @buflen: buffer length
*
* Convert a dentry into an ASCII path name.
*
* Returns a pointer into the buffer or an error code if the
* path was too long.
*
* "buflen" should be positive.
*
* If the path is not reachable from the supplied root, return %NULL.
*/
char *__d_path(const struct path *path,
const struct path *root,
char *buf, int buflen)
{
char *res = buf + buflen;
int error;
prepend(&res, &buflen, "\0", 1);
error = prepend_path(path, root, &res, &buflen);
if (error < 0)
return ERR_PTR(error);
if (error > 0)
return NULL;
return res;
}
char *d_absolute_path(const struct path *path,
char *buf, int buflen)
{
struct path root = {};
char *res = buf + buflen;
int error;
prepend(&res, &buflen, "\0", 1);
error = prepend_path(path, &root, &res, &buflen);
if (error > 1)
error = -EINVAL;
if (error < 0)
return ERR_PTR(error);
return res;
}
/*
* same as __d_path but appends "(deleted)" for unlinked files.
*/
static int path_with_deleted(const struct path *path,
const struct path *root,
char **buf, int *buflen)
{
prepend(buf, buflen, "\0", 1);
if (d_unlinked(path->dentry)) {
int error = prepend(buf, buflen, " (deleted)", 10);
if (error)
return error;
}
return prepend_path(path, root, buf, buflen);
}
static int prepend_unreachable(char **buffer, int *buflen)
{
return prepend(buffer, buflen, "(unreachable)", 13);
}
static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
{
unsigned seq;
do {
seq = read_seqcount_begin(&fs->seq);
*root = fs->root;
} while (read_seqcount_retry(&fs->seq, seq));
}
/**
* d_path - return the path of a dentry
* @path: path to report
* @buf: buffer to return value in
* @buflen: buffer length
*
* Convert a dentry into an ASCII path name. If the entry has been deleted
* the string " (deleted)" is appended. Note that this is ambiguous.
*
* Returns a pointer into the buffer or an error code if the path was
* too long. Note: Callers should use the returned pointer, not the passed
* in buffer, to use the name! The implementation often starts at an offset
* into the buffer, and may leave 0 bytes at the start.
*
* "buflen" should be positive.
*/
char *d_path(const struct path *path, char *buf, int buflen)
{
char *res = buf + buflen;
struct path root;
int error;
/*
* We have various synthetic filesystems that never get mounted. On
* these filesystems dentries are never used for lookup purposes, and
* thus don't need to be hashed. They also don't need a name until a
* user wants to identify the object in /proc/pid/fd/. The little hack
* below allows us to generate a name for these objects on demand:
*
* Some pseudo inodes are mountable. When they are mounted
* path->dentry == path->mnt->mnt_root. In that case don't call d_dname
* and instead have d_path return the mounted path.
*/
if (path->dentry->d_op && path->dentry->d_op->d_dname &&
(!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root))
return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
rcu_read_lock();
get_fs_root_rcu(current->fs, &root);
error = path_with_deleted(path, &root, &res, &buflen);
rcu_read_unlock();
if (error < 0)
res = ERR_PTR(error);
return res;
}
EXPORT_SYMBOL(d_path);
/*
* Helper function for dentry_operations.d_dname() members
*/
char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
const char *fmt, ...)
{
va_list args;
char temp[64];
int sz;
va_start(args, fmt);
sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
va_end(args);
if (sz > sizeof(temp) || sz > buflen)
return ERR_PTR(-ENAMETOOLONG);
buffer += buflen - sz;
return memcpy(buffer, temp, sz);
}
char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
{
char *end = buffer + buflen;
/* these dentries are never renamed, so d_lock is not needed */
if (prepend(&end, &buflen, " (deleted)", 11) ||
prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) ||
prepend(&end, &buflen, "/", 1))
end = ERR_PTR(-ENAMETOOLONG);
return end;
}
EXPORT_SYMBOL(simple_dname);
/*
* Write full pathname from the root of the filesystem into the buffer.
*/
static char *__dentry_path(struct dentry *d, char *buf, int buflen)
{
struct dentry *dentry;
char *end, *retval;
int len, seq = 0;
int error = 0;
if (buflen < 2)
goto Elong;
rcu_read_lock();
restart:
dentry = d;
end = buf + buflen;
len = buflen;
prepend(&end, &len, "\0", 1);
/* Get '/' right */
retval = end-1;
*retval = '/';
read_seqbegin_or_lock(&rename_lock, &seq);
while (!IS_ROOT(dentry)) {
struct dentry *parent = dentry->d_parent;
prefetch(parent);
error = prepend_name(&end, &len, &dentry->d_name);
if (error)
break;
retval = end;
dentry = parent;
}
if (!(seq & 1))
rcu_read_unlock();
if (need_seqretry(&rename_lock, seq)) {
seq = 1;
goto restart;
}
done_seqretry(&rename_lock, seq);
if (error)
goto Elong;
return retval;
Elong:
return ERR_PTR(-ENAMETOOLONG);
}
char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
{
return __dentry_path(dentry, buf, buflen);
}
EXPORT_SYMBOL(dentry_path_raw);
char *dentry_path(struct dentry *dentry, char *buf, int buflen)
{
char *p = NULL;
char *retval;
if (d_unlinked(dentry)) {
p = buf + buflen;
if (prepend(&p, &buflen, "//deleted", 10) != 0)
goto Elong;
buflen++;
}
retval = __dentry_path(dentry, buf, buflen);
if (!IS_ERR(retval) && p)
*p = '/'; /* restore '/' overriden with '\0' */
return retval;
Elong:
return ERR_PTR(-ENAMETOOLONG);
}
static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root,
struct path *pwd)
{
unsigned seq;
do {
seq = read_seqcount_begin(&fs->seq);
*root = fs->root;
*pwd = fs->pwd;
} while (read_seqcount_retry(&fs->seq, seq));
}
/*
* NOTE! The user-level library version returns a
* character pointer. The kernel system call just
* returns the length of the buffer filled (which
* includes the ending '\0' character), or a negative
* error value. So libc would do something like
*
* char *getcwd(char * buf, size_t size)
* {
* int retval;
*
* retval = sys_getcwd(buf, size);
* if (retval >= 0)
* return buf;
* errno = -retval;
* return NULL;
* }
*/
SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
{
int error;
struct path pwd, root;
char *page = __getname();
if (!page)
return -ENOMEM;
rcu_read_lock();
get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
error = -ENOENT;
if (!d_unlinked(pwd.dentry)) {
unsigned long len;
char *cwd = page + PATH_MAX;
int buflen = PATH_MAX;
prepend(&cwd, &buflen, "\0", 1);
error = prepend_path(&pwd, &root, &cwd, &buflen);
rcu_read_unlock();
if (error < 0)
goto out;
/* Unreachable from current root */
if (error > 0) {
error = prepend_unreachable(&cwd, &buflen);
if (error)
goto out;
}
error = -ERANGE;
len = PATH_MAX + page - cwd;
if (len <= size) {
error = len;
if (copy_to_user(buf, cwd, len))
error = -EFAULT;
}
} else {
rcu_read_unlock();
}
out:
__putname(page);
return error;
}
/* /*
* Test whether new_dentry is a subdirectory of old_dentry. * Test whether new_dentry is a subdirectory of old_dentry.
* *
...@@ -3585,6 +3095,8 @@ void d_genocide(struct dentry *parent) ...@@ -3585,6 +3095,8 @@ void d_genocide(struct dentry *parent)
d_walk(parent, parent, d_genocide_kill, NULL); d_walk(parent, parent, d_genocide_kill, NULL);
} }
EXPORT_SYMBOL(d_genocide);
void d_tmpfile(struct dentry *dentry, struct inode *inode) void d_tmpfile(struct dentry *dentry, struct inode *inode)
{ {
inode_dec_link_count(inode); inode_dec_link_count(inode);
...@@ -3664,8 +3176,6 @@ static void __init dcache_init(void) ...@@ -3664,8 +3176,6 @@ static void __init dcache_init(void)
struct kmem_cache *names_cachep __read_mostly; struct kmem_cache *names_cachep __read_mostly;
EXPORT_SYMBOL(names_cachep); EXPORT_SYMBOL(names_cachep);
EXPORT_SYMBOL(d_genocide);
void __init vfs_caches_init_early(void) void __init vfs_caches_init_early(void)
{ {
int i; int i;
......
...@@ -270,10 +270,7 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent) ...@@ -270,10 +270,7 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
if (!parent) if (!parent)
parent = debugfs_mount->mnt_root; parent = debugfs_mount->mnt_root;
inode_lock(d_inode(parent)); dentry = lookup_one_len_unlocked(name, parent, strlen(name));
dentry = lookup_one_len(name, parent, strlen(name));
inode_unlock(d_inode(parent));
if (IS_ERR(dentry)) if (IS_ERR(dentry))
return NULL; return NULL;
if (!d_really_is_positive(dentry)) { if (!d_really_is_positive(dentry)) {
......
...@@ -1474,43 +1474,36 @@ static struct dentry *lookup_dcache(const struct qstr *name, ...@@ -1474,43 +1474,36 @@ static struct dentry *lookup_dcache(const struct qstr *name,
} }
/* /*
* Call i_op->lookup on the dentry. The dentry must be negative and * Parent directory has inode locked exclusive. This is one
* unhashed. * and only case when ->lookup() gets called on non in-lookup
* * dentries - as the matter of fact, this only gets called
* dir->d_inode->i_mutex must be held * when directory is guaranteed to have no in-lookup children
* at all.
*/ */
static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct dentry *old;
/* Don't create child dentry for a dead directory. */
if (unlikely(IS_DEADDIR(dir))) {
dput(dentry);
return ERR_PTR(-ENOENT);
}
old = dir->i_op->lookup(dir, dentry, flags);
if (unlikely(old)) {
dput(dentry);
dentry = old;
}
return dentry;
}
static struct dentry *__lookup_hash(const struct qstr *name, static struct dentry *__lookup_hash(const struct qstr *name,
struct dentry *base, unsigned int flags) struct dentry *base, unsigned int flags)
{ {
struct dentry *dentry = lookup_dcache(name, base, flags); struct dentry *dentry = lookup_dcache(name, base, flags);
struct dentry *old;
struct inode *dir = base->d_inode;
if (dentry) if (dentry)
return dentry; return dentry;
/* Don't create child dentry for a dead directory. */
if (unlikely(IS_DEADDIR(dir)))
return ERR_PTR(-ENOENT);
dentry = d_alloc(base, name); dentry = d_alloc(base, name);
if (unlikely(!dentry)) if (unlikely(!dentry))
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
return lookup_real(base->d_inode, dentry, flags); old = dir->i_op->lookup(dir, dentry, flags);
if (unlikely(old)) {
dput(dentry);
dentry = old;
}
return dentry;
} }
static int lookup_fast(struct nameidata *nd, static int lookup_fast(struct nameidata *nd,
......
...@@ -56,9 +56,7 @@ struct qstr { ...@@ -56,9 +56,7 @@ struct qstr {
#define QSTR_INIT(n,l) { { { .len = l } }, .name = n } #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
extern const char empty_string[];
extern const struct qstr empty_name; extern const struct qstr empty_name;
extern const char slash_string[];
extern const struct qstr slash_name; extern const struct qstr slash_name;
struct dentry_stat_t { struct dentry_stat_t {
...@@ -361,7 +359,7 @@ static inline void dont_mount(struct dentry *dentry) ...@@ -361,7 +359,7 @@ static inline void dont_mount(struct dentry *dentry)
extern void __d_lookup_done(struct dentry *); extern void __d_lookup_done(struct dentry *);
static inline int d_in_lookup(struct dentry *dentry) static inline int d_in_lookup(const struct dentry *dentry)
{ {
return dentry->d_flags & DCACHE_PAR_LOOKUP; return dentry->d_flags & DCACHE_PAR_LOOKUP;
} }
...@@ -489,7 +487,7 @@ static inline bool d_really_is_positive(const struct dentry *dentry) ...@@ -489,7 +487,7 @@ static inline bool d_really_is_positive(const struct dentry *dentry)
return dentry->d_inode != NULL; return dentry->d_inode != NULL;
} }
static inline int simple_positive(struct dentry *dentry) static inline int simple_positive(const struct dentry *dentry)
{ {
return d_really_is_positive(dentry) && !d_unhashed(dentry); return d_really_is_positive(dentry) && !d_unhashed(dentry);
} }
......
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