#include <linux/syscalls.h>
#include <linux/string.h>
#include <linux/mm.h>
+#include <linux/fdtable.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/slab.h>
#include <linux/init.h>
-#include <linux/smp_lock.h>
#include <linux/hash.h>
#include <linux/cache.h>
#include <linux/module.h>
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock);
-static __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
+__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
EXPORT_SYMBOL(dcache_lock);
static unsigned int d_hash_mask __read_mostly;
static unsigned int d_hash_shift __read_mostly;
static struct hlist_head *dentry_hashtable __read_mostly;
-static LIST_HEAD(dentry_unused);
/* Statistics gathering. */
struct dentry_stat_t dentry_stat = {
if (dentry->d_op && dentry->d_op->d_release)
dentry->d_op->d_release(dentry);
/* if dentry was never inserted into hash, immediate free is OK */
- if (dentry->d_hash.pprev == NULL)
+ if (hlist_unhashed(&dentry->d_hash))
__d_free(dentry);
else
call_rcu(&dentry->d_u.d_rcu, d_callback);
/*
* Release the dentry's inode, using the filesystem
* d_iput() operation if defined.
- * Called with dcache_lock and per dentry lock held, drops both.
*/
static void dentry_iput(struct dentry * dentry)
+ __releases(dentry->d_lock)
+ __releases(dcache_lock)
{
struct inode *inode = dentry->d_inode;
if (inode) {
}
}
+/*
+ * dentry_lru_(add|add_tail|del|del_init) must be called with dcache_lock held.
+ */
+static void dentry_lru_add(struct dentry *dentry)
+{
+ list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+ dentry->d_sb->s_nr_dentry_unused++;
+ dentry_stat.nr_unused++;
+}
+
+static void dentry_lru_add_tail(struct dentry *dentry)
+{
+ list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+ dentry->d_sb->s_nr_dentry_unused++;
+ dentry_stat.nr_unused++;
+}
+
+static void dentry_lru_del(struct dentry *dentry)
+{
+ if (!list_empty(&dentry->d_lru)) {
+ list_del(&dentry->d_lru);
+ dentry->d_sb->s_nr_dentry_unused--;
+ dentry_stat.nr_unused--;
+ }
+}
+
+static void dentry_lru_del_init(struct dentry *dentry)
+{
+ if (likely(!list_empty(&dentry->d_lru))) {
+ list_del_init(&dentry->d_lru);
+ dentry->d_sb->s_nr_dentry_unused--;
+ dentry_stat.nr_unused--;
+ }
+}
+
+/**
+ * d_kill - kill dentry and return parent
+ * @dentry: dentry to kill
+ *
+ * The dentry must already be unhashed and removed from the LRU.
+ *
+ * If this is the root of the dentry tree, return NULL.
+ */
+static struct dentry *d_kill(struct dentry *dentry)
+ __releases(dentry->d_lock)
+ __releases(dcache_lock)
+{
+ struct dentry *parent;
+
+ list_del(&dentry->d_u.d_child);
+ dentry_stat.nr_dentry--; /* For d_free, below */
+ /*drops the locks, at that point nobody can reach this dentry */
+ dentry_iput(dentry);
+ parent = dentry->d_parent;
+ d_free(dentry);
+ return dentry == parent ? NULL : parent;
+}
+
/*
* This is dput
*
goto kill_it;
if (list_empty(&dentry->d_lru)) {
dentry->d_flags |= DCACHE_REFERENCED;
- list_add(&dentry->d_lru, &dentry_unused);
- dentry_stat.nr_unused++;
+ dentry_lru_add(dentry);
}
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
unhash_it:
__d_drop(dentry);
-
-kill_it: {
- struct dentry *parent;
-
- /* If dentry was on d_lru list
- * delete it from there
- */
- if (!list_empty(&dentry->d_lru)) {
- list_del(&dentry->d_lru);
- dentry_stat.nr_unused--;
- }
- list_del(&dentry->d_u.d_child);
- dentry_stat.nr_dentry--; /* For d_free, below */
- /*drops the locks, at that point nobody can reach this dentry */
- dentry_iput(dentry);
- parent = dentry->d_parent;
- d_free(dentry);
- if (dentry == parent)
- return;
- dentry = parent;
+kill_it:
+ /* if dentry was on the d_lru list delete it from there */
+ dentry_lru_del(dentry);
+ dentry = d_kill(dentry);
+ if (dentry)
goto repeat;
- }
}
/**
static inline struct dentry * __dget_locked(struct dentry *dentry)
{
atomic_inc(&dentry->d_count);
- if (!list_empty(&dentry->d_lru)) {
- dentry_stat.nr_unused--;
- list_del_init(&dentry->d_lru);
- }
+ dentry_lru_del_init(dentry);
return dentry;
}
* Throw away a dentry - free the inode, dput the parent. This requires that
* the LRU list has already been removed.
*
- * Called with dcache_lock, drops it and then regains.
- * Called with dentry->d_lock held, drops it.
+ * Try to prune ancestors as well. This is necessary to prevent
+ * quadratic behavior of shrink_dcache_parent(), but is also expected
+ * to be beneficial in reducing dentry cache fragmentation.
*/
static void prune_one_dentry(struct dentry * dentry)
+ __releases(dentry->d_lock)
+ __releases(dcache_lock)
+ __acquires(dcache_lock)
{
- struct dentry * parent;
-
__d_drop(dentry);
- list_del(&dentry->d_u.d_child);
- dentry_stat.nr_dentry--; /* For d_free, below */
- dentry_iput(dentry);
- parent = dentry->d_parent;
- d_free(dentry);
- if (parent != dentry)
- dput(parent);
+ dentry = d_kill(dentry);
+
+ /*
+ * Prune ancestors. Locking is simpler than in dput(),
+ * because dcache_lock needs to be taken anyway.
+ */
spin_lock(&dcache_lock);
+ while (dentry) {
+ if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock))
+ return;
+
+ if (dentry->d_op && dentry->d_op->d_delete)
+ dentry->d_op->d_delete(dentry);
+ dentry_lru_del_init(dentry);
+ __d_drop(dentry);
+ dentry = d_kill(dentry);
+ spin_lock(&dcache_lock);
+ }
}
-/**
- * prune_dcache - shrink the dcache
- * @count: number of entries to try and free
- * @sb: if given, ignore dentries for other superblocks
- * which are being unmounted.
- *
- * Shrink the dcache. This is done when we need
- * more memory, or simply when we need to unmount
- * something (at which point we need to unuse
- * all dentries).
- *
- * This function may fail to free any resources if
- * all the dentries are in use.
+/*
+ * Shrink the dentry LRU on a given superblock.
+ * @sb : superblock to shrink dentry LRU.
+ * @count: If count is NULL, we prune all dentries on superblock.
+ * @flags: If flags is non-zero, we need to do special processing based on
+ * which flags are set. This means we don't need to maintain multiple
+ * similar copies of this loop.
*/
-
-static void prune_dcache(int count, struct super_block *sb)
+static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
{
- spin_lock(&dcache_lock);
- for (; count ; count--) {
- struct dentry *dentry;
- struct list_head *tmp;
- struct rw_semaphore *s_umount;
-
- cond_resched_lock(&dcache_lock);
+ LIST_HEAD(referenced);
+ LIST_HEAD(tmp);
+ struct dentry *dentry;
+ int cnt = 0;
- tmp = dentry_unused.prev;
- if (sb) {
- /* Try to find a dentry for this sb, but don't try
- * too hard, if they aren't near the tail they will
- * be moved down again soon
+ BUG_ON(!sb);
+ BUG_ON((flags & DCACHE_REFERENCED) && count == NULL);
+ spin_lock(&dcache_lock);
+ if (count != NULL)
+ /* called from prune_dcache() and shrink_dcache_parent() */
+ cnt = *count;
+restart:
+ if (count == NULL)
+ list_splice_init(&sb->s_dentry_lru, &tmp);
+ else {
+ while (!list_empty(&sb->s_dentry_lru)) {
+ dentry = list_entry(sb->s_dentry_lru.prev,
+ struct dentry, d_lru);
+ BUG_ON(dentry->d_sb != sb);
+
+ spin_lock(&dentry->d_lock);
+ /*
+ * If we are honouring the DCACHE_REFERENCED flag and
+ * the dentry has this flag set, don't free it. Clear
+ * the flag and put it back on the LRU.
*/
- int skip = count;
- while (skip && tmp != &dentry_unused &&
- list_entry(tmp, struct dentry, d_lru)->d_sb != sb) {
- skip--;
- tmp = tmp->prev;
+ if ((flags & DCACHE_REFERENCED)
+ && (dentry->d_flags & DCACHE_REFERENCED)) {
+ dentry->d_flags &= ~DCACHE_REFERENCED;
+ list_move_tail(&dentry->d_lru, &referenced);
+ spin_unlock(&dentry->d_lock);
+ } else {
+ list_move_tail(&dentry->d_lru, &tmp);
+ spin_unlock(&dentry->d_lock);
+ cnt--;
+ if (!cnt)
+ break;
}
}
- if (tmp == &dentry_unused)
- break;
- list_del_init(tmp);
- prefetch(dentry_unused.prev);
- dentry_stat.nr_unused--;
- dentry = list_entry(tmp, struct dentry, d_lru);
-
- spin_lock(&dentry->d_lock);
+ }
+ while (!list_empty(&tmp)) {
+ dentry = list_entry(tmp.prev, struct dentry, d_lru);
+ dentry_lru_del_init(dentry);
+ spin_lock(&dentry->d_lock);
/*
* We found an inuse dentry which was not removed from
- * dentry_unused because of laziness during lookup. Do not free
- * it - just keep it off the dentry_unused list.
+ * the LRU because of laziness during lookup. Do not free
+ * it - just keep it off the LRU list.
*/
- if (atomic_read(&dentry->d_count)) {
- spin_unlock(&dentry->d_lock);
+ if (atomic_read(&dentry->d_count)) {
+ spin_unlock(&dentry->d_lock);
continue;
}
- /* If the dentry was recently referenced, don't free it. */
- if (dentry->d_flags & DCACHE_REFERENCED) {
- dentry->d_flags &= ~DCACHE_REFERENCED;
- list_add(&dentry->d_lru, &dentry_unused);
- dentry_stat.nr_unused++;
- spin_unlock(&dentry->d_lock);
+ prune_one_dentry(dentry);
+ /* dentry->d_lock was dropped in prune_one_dentry() */
+ cond_resched_lock(&dcache_lock);
+ }
+ if (count == NULL && !list_empty(&sb->s_dentry_lru))
+ goto restart;
+ if (count != NULL)
+ *count = cnt;
+ if (!list_empty(&referenced))
+ list_splice(&referenced, &sb->s_dentry_lru);
+ spin_unlock(&dcache_lock);
+}
+
+/**
+ * prune_dcache - shrink the dcache
+ * @count: number of entries to try to free
+ *
+ * Shrink the dcache. This is done when we need more memory, or simply when we
+ * need to unmount something (at which point we need to unuse all dentries).
+ *
+ * This function may fail to free any resources if all the dentries are in use.
+ */
+static void prune_dcache(int count)
+{
+ struct super_block *sb;
+ int w_count;
+ int unused = dentry_stat.nr_unused;
+ int prune_ratio;
+ int pruned;
+
+ if (unused == 0 || count == 0)
+ return;
+ spin_lock(&dcache_lock);
+restart:
+ if (count >= unused)
+ prune_ratio = 1;
+ else
+ prune_ratio = unused / count;
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (sb->s_nr_dentry_unused == 0)
continue;
- }
- /*
- * If the dentry is not DCACHED_REFERENCED, it is time
- * to remove it from the dcache, provided the super block is
- * NULL (which means we are trying to reclaim memory)
- * or this dentry belongs to the same super block that
- * we want to shrink.
+ sb->s_count++;
+ /* Now, we reclaim unused dentrins with fairness.
+ * We reclaim them same percentage from each superblock.
+ * We calculate number of dentries to scan on this sb
+ * as follows, but the implementation is arranged to avoid
+ * overflows:
+ * number of dentries to scan on this sb =
+ * count * (number of dentries on this sb /
+ * number of dentries in the machine)
*/
+ spin_unlock(&sb_lock);
+ if (prune_ratio != 1)
+ w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1;
+ else
+ w_count = sb->s_nr_dentry_unused;
+ pruned = w_count;
/*
- * If this dentry is for "my" filesystem, then I can prune it
- * without taking the s_umount lock (I already hold it).
- */
- if (sb && dentry->d_sb == sb) {
- prune_one_dentry(dentry);
- continue;
- }
- /*
- * ...otherwise we need to be sure this filesystem isn't being
- * unmounted, otherwise we could race with
- * generic_shutdown_super(), and end up holding a reference to
- * an inode while the filesystem is unmounted.
- * So we try to get s_umount, and make sure s_root isn't NULL.
- * (Take a local copy of s_umount to avoid a use-after-free of
- * `dentry').
+ * We need to be sure this filesystem isn't being unmounted,
+ * otherwise we could race with generic_shutdown_super(), and
+ * end up holding a reference to an inode while the filesystem
+ * is unmounted. So we try to get s_umount, and make sure
+ * s_root isn't NULL.
*/
- s_umount = &dentry->d_sb->s_umount;
- if (down_read_trylock(s_umount)) {
- if (dentry->d_sb->s_root != NULL) {
- prune_one_dentry(dentry);
- up_read(s_umount);
- continue;
+ if (down_read_trylock(&sb->s_umount)) {
+ if ((sb->s_root != NULL) &&
+ (!list_empty(&sb->s_dentry_lru))) {
+ spin_unlock(&dcache_lock);
+ __shrink_dcache_sb(sb, &w_count,
+ DCACHE_REFERENCED);
+ pruned -= w_count;
+ spin_lock(&dcache_lock);
}
- up_read(s_umount);
+ up_read(&sb->s_umount);
}
- spin_unlock(&dentry->d_lock);
+ spin_lock(&sb_lock);
+ count -= pruned;
/*
- * Insert dentry at the head of the list as inserting at the
- * tail leads to a cycle.
+ * restart only when sb is no longer on the list and
+ * we have more work to do.
*/
- list_add(&dentry->d_lru, &dentry_unused);
- dentry_stat.nr_unused++;
+ if (__put_super_and_need_restart(sb) && count > 0) {
+ spin_unlock(&sb_lock);
+ goto restart;
+ }
}
+ spin_unlock(&sb_lock);
spin_unlock(&dcache_lock);
}
-/*
- * Shrink the dcache for the specified super block.
- * This allows us to unmount a device without disturbing
- * the dcache for the other devices.
- *
- * This implementation makes just two traversals of the
- * unused list. On the first pass we move the selected
- * dentries to the most recent end, and on the second
- * pass we free them. The second pass must restart after
- * each dput(), but since the target dentries are all at
- * the end, it's really just a single traversal.
- */
-
/**
* shrink_dcache_sb - shrink dcache for a superblock
* @sb: superblock
* is used to free the dcache before unmounting a file
* system
*/
-
void shrink_dcache_sb(struct super_block * sb)
{
- struct list_head *tmp, *next;
- struct dentry *dentry;
-
- /*
- * Pass one ... move the dentries for the specified
- * superblock to the most recent end of the unused list.
- */
- spin_lock(&dcache_lock);
- list_for_each_safe(tmp, next, &dentry_unused) {
- dentry = list_entry(tmp, struct dentry, d_lru);
- if (dentry->d_sb != sb)
- continue;
- list_move(tmp, &dentry_unused);
- }
-
- /*
- * Pass two ... free the dentries for this superblock.
- */
-repeat:
- list_for_each_safe(tmp, next, &dentry_unused) {
- dentry = list_entry(tmp, struct dentry, d_lru);
- if (dentry->d_sb != sb)
- continue;
- dentry_stat.nr_unused--;
- list_del_init(tmp);
- spin_lock(&dentry->d_lock);
- if (atomic_read(&dentry->d_count)) {
- spin_unlock(&dentry->d_lock);
- continue;
- }
- prune_one_dentry(dentry);
- cond_resched_lock(&dcache_lock);
- goto repeat;
- }
- spin_unlock(&dcache_lock);
+ __shrink_dcache_sb(sb, NULL, 0);
}
/*
/* detach this root from the system */
spin_lock(&dcache_lock);
- if (!list_empty(&dentry->d_lru)) {
- dentry_stat.nr_unused--;
- list_del_init(&dentry->d_lru);
- }
+ dentry_lru_del_init(dentry);
__d_drop(dentry);
spin_unlock(&dcache_lock);
spin_lock(&dcache_lock);
list_for_each_entry(loop, &dentry->d_subdirs,
d_u.d_child) {
- if (!list_empty(&loop->d_lru)) {
- dentry_stat.nr_unused--;
- list_del_init(&loop->d_lru);
- }
-
+ dentry_lru_del_init(loop);
__d_drop(loop);
cond_resched_lock(&dcache_lock);
}
struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
next = tmp->next;
- if (!list_empty(&dentry->d_lru)) {
- dentry_stat.nr_unused--;
- list_del_init(&dentry->d_lru);
- }
+ dentry_lru_del_init(dentry);
/*
* move only zero ref count dentries to the end
* of the unused list for prune_dcache
*/
if (!atomic_read(&dentry->d_count)) {
- list_add_tail(&dentry->d_lru, &dentry_unused);
- dentry_stat.nr_unused++;
+ dentry_lru_add_tail(dentry);
found++;
}
void shrink_dcache_parent(struct dentry * parent)
{
+ struct super_block *sb = parent->d_sb;
int found;
while ((found = select_parent(parent)) != 0)
- prune_dcache(found, parent->d_sb);
+ __shrink_dcache_sb(sb, &found, 0);
}
/*
if (nr) {
if (!(gfp_mask & __GFP_FS))
return -1;
- prune_dcache(nr, NULL);
+ prune_dcache(nr);
}
return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
}
+static struct shrinker dcache_shrinker = {
+ .shrink = shrink_dcache_memory,
+ .seeks = DEFAULT_SEEKS,
+};
+
/**
* d_alloc - allocate a dcache entry
* @parent: parent of entry to allocate
struct dentry *dentry;
char *dname;
- dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
+ dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
if (!dentry)
return NULL;
* rcu_read_lock() and rcu_read_unlock() are used to disable preemption while
* lookup is going on.
*
- * dentry_unused list is not updated even if lookup finds the required dentry
+ * The dentry unused LRU is not updated even if lookup finds the required dentry
* in there. It is updated in places such as prune_dcache, shrink_dcache_sb,
* select_parent and __dget_locked. This laziness saves lookup from dcache_lock
* acquisition.
if (atomic_read(&dentry->d_count) == 1) {
dentry_iput(dentry);
fsnotify_nameremove(dentry, isdir);
-
- /* remove this and other inotify debug checks after 2.6.18 */
- dentry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED;
return;
}
* dentry:internal, target:external. Steal target's
* storage and make target internal.
*/
+ memcpy(target->d_iname, dentry->d_name.name,
+ dentry->d_name.len + 1);
dentry->d_name.name = target->d_name.name;
target->d_name.name = target->d_iname;
}
* This forceful removal will result in ugly /proc output if
* somebody holds a file open that got deleted due to a rename.
* We could be nicer about the deleted file, and let it show
- * up under the name it got deleted rather than the name that
- * deleted it.
+ * up under the name it had before it was deleted rather than
+ * under the original name of the file that was moved on top of it.
*/
/*
}
/* Move the dentry to the target hash queue, if on different bucket */
- if (dentry->d_flags & DCACHE_UNHASHED)
+ if (d_unhashed(dentry))
goto already_unhashed;
hlist_del_rcu(&dentry->d_hash);
*
* Note: If ever the locking in lock_rename() changes, then please
* remember to update this too...
- *
- * On return, dcache_lock will have been unlocked.
*/
static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
+ __releases(dcache_lock)
{
struct mutex *m1 = NULL, *m2 = NULL;
struct dentry *ret;
shouldnt_be_hashed:
spin_unlock(&dcache_lock);
BUG();
- goto shouldnt_be_hashed;
+}
+
+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;
+}
+
+static int prepend_name(char **buffer, int *buflen, struct qstr *name)
+{
+ return prepend(buffer, buflen, name->name, name->len);
}
/**
- * d_path - return the path of a dentry
- * @dentry: dentry to report
- * @vfsmnt: vfsmnt to which the dentry belongs
- * @root: root dentry
- * @rootmnt: vfsmnt to which the root dentry belongs
+ * __d_path - return the path of a dentry
+ * @path: the dentry/vfsmount to report
+ * @root: root vfsmnt/dentry (may be modified by this function)
* @buffer: buffer to return value in
* @buflen: buffer length
- * @fail_deleted: what to return for deleted files
*
- * Convert a dentry into an ASCII path name. If the entry has been deleted,
- * then if @fail_deleted is true, ERR_PTR(-ENOENT) is returned. Otherwise,
- * the the string " (deleted)" is appended. Note that this is ambiguous.
+ * 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 the buffer or an error code.
+ * Returns the buffer or an error code if the path was too long.
+ *
+ * "buflen" should be positive. Caller holds the dcache_lock.
+ *
+ * If path is not reachable from the supplied root, then the value of
+ * root is changed (without modifying refcounts).
*/
-static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
- struct dentry *root, struct vfsmount *rootmnt,
- char *buffer, int buflen, int fail_deleted)
+char *__d_path(const struct path *path, struct path *root,
+ char *buffer, int buflen)
{
- int namelen, is_slash;
+ struct dentry *dentry = path->dentry;
+ struct vfsmount *vfsmnt = path->mnt;
+ char *end = buffer + buflen;
+ char *retval;
+
+ spin_lock(&vfsmount_lock);
+ prepend(&end, &buflen, "\0", 1);
+ if (!IS_ROOT(dentry) && d_unhashed(dentry) &&
+ (prepend(&end, &buflen, " (deleted)", 10) != 0))
+ goto Elong;
- if (buflen < 2)
- return ERR_PTR(-ENAMETOOLONG);
- buffer += --buflen;
- *buffer = '\0';
+ if (buflen < 1)
+ goto Elong;
+ /* Get '/' right */
+ retval = end-1;
+ *retval = '/';
- spin_lock(&dcache_lock);
- if (!IS_ROOT(dentry) && d_unhashed(dentry)) {
- if (fail_deleted) {
- buffer = ERR_PTR(-ENOENT);
- goto out;
- }
- if (buflen < 10)
- goto Elong;
- buflen -= 10;
- buffer -= 10;
- memcpy(buffer, " (deleted)", 10);
- }
- while (dentry != root || vfsmnt != rootmnt) {
+ for (;;) {
struct dentry * parent;
+ if (dentry == root->dentry && vfsmnt == root->mnt)
+ break;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
- spin_lock(&vfsmount_lock);
+ /* Global root? */
if (vfsmnt->mnt_parent == vfsmnt) {
- spin_unlock(&vfsmount_lock);
goto global_root;
}
dentry = vfsmnt->mnt_mountpoint;
vfsmnt = vfsmnt->mnt_parent;
- spin_unlock(&vfsmount_lock);
continue;
}
parent = dentry->d_parent;
prefetch(parent);
- namelen = dentry->d_name.len;
- if (buflen <= namelen)
+ if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) ||
+ (prepend(&end, &buflen, "/", 1) != 0))
goto Elong;
- buflen -= namelen + 1;
- buffer -= namelen;
- memcpy(buffer, dentry->d_name.name, namelen);
- *--buffer = '/';
+ retval = end;
dentry = parent;
}
- /* Get '/' right */
- if (*buffer != '/')
- *--buffer = '/';
out:
- spin_unlock(&dcache_lock);
- return buffer;
+ spin_unlock(&vfsmount_lock);
+ return retval;
global_root:
- /*
- * We went past the (vfsmount, dentry) we were looking for and have
- * either hit a root dentry, a lazily unmounted dentry, an
- * unconnected dentry, or the file is on a pseudo filesystem.
- */
- namelen = dentry->d_name.len;
- is_slash = (namelen == 1 && *dentry->d_name.name == '/');
- if (is_slash || (dentry->d_sb->s_flags & MS_NOUSER)) {
- /*
- * Make sure we won't return a pathname starting with '/'.
- *
- * Historically, we also glue together the root dentry and
- * remaining name for pseudo filesystems like pipefs, which
- * have the MS_NOUSER flag set. This results in pathnames
- * like "pipe:[439336]".
- */
- if (*buffer == '/') {
- buffer++;
- buflen++;
- }
- if (is_slash)
- goto out;
- }
- if (buflen < namelen)
+ retval += 1; /* hit the slash */
+ if (prepend_name(&retval, &buflen, &dentry->d_name) != 0)
goto Elong;
- buffer -= namelen;
- memcpy(buffer, dentry->d_name.name, namelen);
+ root->mnt = vfsmnt;
+ root->dentry = dentry;
goto out;
Elong:
- buffer = ERR_PTR(-ENAMETOOLONG);
+ retval = ERR_PTR(-ENAMETOOLONG);
goto out;
}
-/* write full pathname into buffer and return start of pathname */
-char *d_path(struct dentry *dentry, struct vfsmount *vfsmnt, char *buf,
- int buflen)
+/**
+ * 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 the buffer or an error code if the path was too long.
+ *
+ * "buflen" should be positive.
+ */
+char *d_path(const struct path *path, char *buf, int buflen)
{
char *res;
- struct vfsmount *rootmnt;
- struct dentry *root;
+ struct path root;
+ struct path tmp;
+
+ /*
+ * 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:
+ */
+ if (path->dentry->d_op && path->dentry->d_op->d_dname)
+ return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
read_lock(¤t->fs->lock);
- rootmnt = mntget(current->fs->rootmnt);
- root = dget(current->fs->root);
+ root = current->fs->root;
+ path_get(&root);
read_unlock(¤t->fs->lock);
- res = __d_path(dentry, vfsmnt, root, rootmnt, buf, buflen, 0);
- dput(root);
- mntput(rootmnt);
+ spin_lock(&dcache_lock);
+ tmp = root;
+ res = __d_path(path, &tmp, buf, buflen);
+ spin_unlock(&dcache_lock);
+ path_put(&root);
return res;
}
+/*
+ * 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);
+}
+
+/*
+ * Write full pathname from the root of the filesystem into the buffer.
+ */
+char *dentry_path(struct dentry *dentry, char *buf, int buflen)
+{
+ char *end = buf + buflen;
+ char *retval;
+
+ spin_lock(&dcache_lock);
+ prepend(&end, &buflen, "\0", 1);
+ if (!IS_ROOT(dentry) && d_unhashed(dentry) &&
+ (prepend(&end, &buflen, "//deleted", 9) != 0))
+ goto Elong;
+ if (buflen < 1)
+ goto Elong;
+ /* Get '/' right */
+ retval = end-1;
+ *retval = '/';
+
+ while (!IS_ROOT(dentry)) {
+ struct dentry *parent = dentry->d_parent;
+
+ prefetch(parent);
+ if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) ||
+ (prepend(&end, &buflen, "/", 1) != 0))
+ goto Elong;
+
+ retval = end;
+ dentry = parent;
+ }
+ spin_unlock(&dcache_lock);
+ return retval;
+Elong:
+ spin_unlock(&dcache_lock);
+ return ERR_PTR(-ENAMETOOLONG);
+}
+
/*
* NOTE! The user-level library version returns a
* character pointer. The kernel system call just
*/
asmlinkage long sys_getcwd(char __user *buf, unsigned long size)
{
- int error, len;
- struct vfsmount *pwdmnt, *rootmnt;
- struct dentry *pwd, *root;
- char *page = (char *) __get_free_page(GFP_USER), *cwd;
+ int error;
+ struct path pwd, root;
+ char *page = (char *) __get_free_page(GFP_USER);
if (!page)
return -ENOMEM;
read_lock(¤t->fs->lock);
- pwdmnt = mntget(current->fs->pwdmnt);
- pwd = dget(current->fs->pwd);
- rootmnt = mntget(current->fs->rootmnt);
- root = dget(current->fs->root);
+ pwd = current->fs->pwd;
+ path_get(&pwd);
+ root = current->fs->root;
+ path_get(&root);
read_unlock(¤t->fs->lock);
- cwd = __d_path(pwd, pwdmnt, root, rootmnt, page, PAGE_SIZE, 1);
- error = PTR_ERR(cwd);
- if (IS_ERR(cwd))
- goto out;
+ error = -ENOENT;
+ /* Has the current directory has been unlinked? */
+ spin_lock(&dcache_lock);
+ if (IS_ROOT(pwd.dentry) || !d_unhashed(pwd.dentry)) {
+ unsigned long len;
+ struct path tmp = root;
+ char * cwd;
- error = -ERANGE;
- len = PAGE_SIZE + page - cwd;
- if (len <= size) {
- error = len;
- if (copy_to_user(buf, cwd, len))
- error = -EFAULT;
- }
+ cwd = __d_path(&pwd, &tmp, page, PAGE_SIZE);
+ spin_unlock(&dcache_lock);
+
+ error = PTR_ERR(cwd);
+ if (IS_ERR(cwd))
+ goto out;
+
+ error = -ERANGE;
+ len = PAGE_SIZE + page - cwd;
+ if (len <= size) {
+ error = len;
+ if (copy_to_user(buf, cwd, len))
+ error = -EFAULT;
+ }
+ } else
+ spin_unlock(&dcache_lock);
out:
- dput(pwd);
- mntput(pwdmnt);
- dput(root);
- mntput(rootmnt);
+ path_put(&pwd);
+ path_put(&root);
free_page((unsigned long) page);
return error;
}
INIT_HLIST_HEAD(&dentry_hashtable[loop]);
}
-static void __init dcache_init(unsigned long mempages)
+static void __init dcache_init(void)
{
int loop;
* but it is probably not worth it because of the cache nature
* of the dcache.
*/
- dentry_cache = kmem_cache_create("dentry_cache",
- sizeof(struct dentry),
- 0,
- (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
- SLAB_MEM_SPREAD),
- NULL, NULL);
+ dentry_cache = KMEM_CACHE(dentry,
+ SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
- set_shrinker(DEFAULT_SEEKS, shrink_dcache_memory);
+ register_shrinker(&dcache_shrinker);
/* Hash may have been set up in dcache_init_early */
if (!hashdist)
mempages -= reserve;
names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
- dcache_init(mempages);
- inode_init(mempages);
+ dcache_init();
+ inode_init();
files_init(mempages);
- mnt_init(mempages);
+ mnt_init();
bdev_cache_init();
chrdev_init();
}