*
* Copyright (C) 2000,2001,2002 Stephen Rothwell
*
+ * Copyright (C) 2009 Eric Paris <Red Hat Inc>
+ * dnotify was largly rewritten to use the new fsnotify infrastructure
+ *
* This program 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, or (at your option) any
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/fdtable.h>
+#include <linux/fsnotify_backend.h>
int dir_notify_enable __read_mostly = 1;
-static struct kmem_cache *dn_cache __read_mostly;
+static struct kmem_cache *dnotify_struct_cache __read_mostly;
+static struct kmem_cache *dnotify_mark_entry_cache __read_mostly;
+static struct fsnotify_group *dnotify_group __read_mostly;
+static DEFINE_MUTEX(dnotify_mark_mutex);
+
+/*
+ * dnotify will attach one of these to each inode (i_fsnotify_mark_entries) which
+ * is being watched by dnotify. If multiple userspace applications are watching
+ * the same directory with dnotify their information is chained in dn
+ */
+struct dnotify_mark_entry {
+ struct fsnotify_mark_entry fsn_entry;
+ struct dnotify_struct *dn;
+};
-static void redo_inode_mask(struct inode *inode)
+/*
+ * When a process starts or stops watching an inode the set of events which
+ * dnotify cares about for that inode may change. This function runs the
+ * list of everything receiving dnotify events about this directory and calculates
+ * the set of all those events. After it updates what dnotify is interested in
+ * it calls the fsnotify function so it can update the set of all events relevant
+ * to this inode.
+ */
+static void dnotify_recalc_inode_mask(struct fsnotify_mark_entry *entry)
{
- unsigned long new_mask;
+ __u32 new_mask, old_mask;
struct dnotify_struct *dn;
+ struct dnotify_mark_entry *dnentry = container_of(entry,
+ struct dnotify_mark_entry,
+ fsn_entry);
+
+ assert_spin_locked(&entry->lock);
+ old_mask = entry->mask;
new_mask = 0;
- for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
- new_mask |= dn->dn_mask & ~DN_MULTISHOT;
- inode->i_dnotify_mask = new_mask;
+ for (dn = dnentry->dn; dn != NULL; dn = dn->dn_next)
+ new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT);
+ entry->mask = new_mask;
+
+ if (old_mask == new_mask)
+ return;
+
+ if (entry->inode)
+ fsnotify_recalc_inode_mask(entry->inode);
}
+/*
+ * Mains fsnotify call where events are delivered to dnotify.
+ * Find the dnotify mark on the relevant inode, run the list of dnotify structs
+ * on that mark and determine which of them has expressed interest in receiving
+ * events of this type. When found send the correct process and signal and
+ * destroy the dnotify struct if it was not registered to receive multiple
+ * events.
+ */
+static int dnotify_handle_event(struct fsnotify_group *group,
+ struct fsnotify_event *event)
+{
+ struct fsnotify_mark_entry *entry = NULL;
+ struct dnotify_mark_entry *dnentry;
+ struct inode *to_tell;
+ struct dnotify_struct *dn;
+ struct dnotify_struct **prev;
+ struct fown_struct *fown;
+
+ to_tell = event->to_tell;
+
+ spin_lock(&to_tell->i_lock);
+ entry = fsnotify_find_mark_entry(group, to_tell);
+ spin_unlock(&to_tell->i_lock);
+
+ /* unlikely since we alreay passed dnotify_should_send_event() */
+ if (unlikely(!entry))
+ return 0;
+ dnentry = container_of(entry, struct dnotify_mark_entry, fsn_entry);
+
+ spin_lock(&entry->lock);
+ prev = &dnentry->dn;
+ while ((dn = *prev) != NULL) {
+ if ((dn->dn_mask & event->mask) == 0) {
+ prev = &dn->dn_next;
+ continue;
+ }
+ fown = &dn->dn_filp->f_owner;
+ send_sigio(fown, dn->dn_fd, POLL_MSG);
+ if (dn->dn_mask & FS_DN_MULTISHOT)
+ prev = &dn->dn_next;
+ else {
+ *prev = dn->dn_next;
+ kmem_cache_free(dnotify_struct_cache, dn);
+ dnotify_recalc_inode_mask(entry);
+ }
+ }
+
+ spin_unlock(&entry->lock);
+ fsnotify_put_mark(entry);
+
+ return 0;
+}
+
+/*
+ * Given an inode and mask determine if dnotify would be interested in sending
+ * userspace notification for that pair.
+ */
+static bool dnotify_should_send_event(struct fsnotify_group *group,
+ struct inode *inode, __u32 mask)
+{
+ struct fsnotify_mark_entry *entry;
+ bool send;
+
+ /* !dir_notify_enable should never get here, don't waste time checking
+ if (!dir_notify_enable)
+ return 0; */
+
+ /* not a dir, dnotify doesn't care */
+ if (!S_ISDIR(inode->i_mode))
+ return false;
+
+ spin_lock(&inode->i_lock);
+ entry = fsnotify_find_mark_entry(group, inode);
+ spin_unlock(&inode->i_lock);
+
+ /* no mark means no dnotify watch */
+ if (!entry)
+ return false;
+
+ spin_lock(&entry->lock);
+ send = (mask & entry->mask) ? true : false;
+ spin_unlock(&entry->lock);
+ fsnotify_put_mark(entry); /* matches fsnotify_find_mark_entry */
+
+ return send;
+}
+
+static void dnotify_freeing_mark(struct fsnotify_mark_entry *entry,
+ struct fsnotify_group *group)
+{
+ /* dnotify doesn't care than an inode is on the way out */
+}
+
+static void dnotify_free_mark(struct fsnotify_mark_entry *entry)
+{
+ struct dnotify_mark_entry *dnentry = container_of(entry,
+ struct dnotify_mark_entry,
+ fsn_entry);
+
+ BUG_ON(dnentry->dn);
+
+ kmem_cache_free(dnotify_mark_entry_cache, dnentry);
+}
+
+static struct fsnotify_ops dnotify_fsnotify_ops = {
+ .handle_event = dnotify_handle_event,
+ .should_send_event = dnotify_should_send_event,
+ .free_group_priv = NULL,
+ .freeing_mark = dnotify_freeing_mark,
+};
+
+/*
+ * Called every time a file is closed. Looks first for a dnotify mark on the
+ * inode. If one is found run all of the ->dn entries attached to that
+ * mark for one relevant to this process closing the file and remove that
+ * dnotify_struct. If that was the last dnotify_struct also remove the
+ * fsnotify_mark_entry.
+ */
void dnotify_flush(struct file *filp, fl_owner_t id)
{
+ struct fsnotify_mark_entry *entry;
+ struct dnotify_mark_entry *dnentry;
struct dnotify_struct *dn;
struct dnotify_struct **prev;
struct inode *inode;
inode = filp->f_path.dentry->d_inode;
if (!S_ISDIR(inode->i_mode))
return;
+
spin_lock(&inode->i_lock);
- prev = &inode->i_dnotify;
+ entry = fsnotify_find_mark_entry(dnotify_group, inode);
+ spin_unlock(&inode->i_lock);
+ if (!entry)
+ return;
+ dnentry = container_of(entry, struct dnotify_mark_entry, fsn_entry);
+
+ mutex_lock(&dnotify_mark_mutex);
+
+ spin_lock(&entry->lock);
+ prev = &dnentry->dn;
while ((dn = *prev) != NULL) {
if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
*prev = dn->dn_next;
- redo_inode_mask(inode);
- kmem_cache_free(dn_cache, dn);
+ kmem_cache_free(dnotify_struct_cache, dn);
+ dnotify_recalc_inode_mask(entry);
break;
}
prev = &dn->dn_next;
}
- spin_unlock(&inode->i_lock);
+
+ spin_unlock(&entry->lock);
+
+ /* nothing else could have found us thanks to the dnotify_mark_mutex */
+ if (dnentry->dn == NULL)
+ fsnotify_destroy_mark_by_entry(entry);
+
+ fsnotify_recalc_group_mask(dnotify_group);
+
+ mutex_unlock(&dnotify_mark_mutex);
+
+ fsnotify_put_mark(entry);
+}
+
+/* this conversion is done only at watch creation */
+static __u32 convert_arg(unsigned long arg)
+{
+ __u32 new_mask = FS_EVENT_ON_CHILD;
+
+ if (arg & DN_MULTISHOT)
+ new_mask |= FS_DN_MULTISHOT;
+ if (arg & DN_DELETE)
+ new_mask |= (FS_DELETE | FS_MOVED_FROM);
+ if (arg & DN_MODIFY)
+ new_mask |= FS_MODIFY;
+ if (arg & DN_ACCESS)
+ new_mask |= FS_ACCESS;
+ if (arg & DN_ATTRIB)
+ new_mask |= FS_ATTRIB;
+ if (arg & DN_RENAME)
+ new_mask |= FS_DN_RENAME;
+ if (arg & DN_CREATE)
+ new_mask |= (FS_CREATE | FS_MOVED_TO);
+
+ return new_mask;
}
+/*
+ * If multiple processes watch the same inode with dnotify there is only one
+ * dnotify mark in inode->i_fsnotify_mark_entries but we chain a dnotify_struct
+ * onto that mark. This function either attaches the new dnotify_struct onto
+ * that list, or it |= the mask onto an existing dnofiy_struct.
+ */
+static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark_entry *dnentry,
+ fl_owner_t id, int fd, struct file *filp, __u32 mask)
+{
+ struct dnotify_struct *odn;
+
+ odn = dnentry->dn;
+ while (odn != NULL) {
+ /* adding more events to existing dnofiy_struct? */
+ if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
+ odn->dn_fd = fd;
+ odn->dn_mask |= mask;
+ return -EEXIST;
+ }
+ odn = odn->dn_next;
+ }
+
+ dn->dn_mask = mask;
+ dn->dn_fd = fd;
+ dn->dn_filp = filp;
+ dn->dn_owner = id;
+ dn->dn_next = dnentry->dn;
+ dnentry->dn = dn;
+
+ return 0;
+}
+
+/*
+ * When a process calls fcntl to attach a dnotify watch to a directory it ends
+ * up here. Allocate both a mark for fsnotify to add and a dnotify_struct to be
+ * attached to the fsnotify_mark.
+ */
int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
{
+ struct dnotify_mark_entry *new_dnentry, *dnentry;
+ struct fsnotify_mark_entry *new_entry, *entry;
struct dnotify_struct *dn;
- struct dnotify_struct *odn;
- struct dnotify_struct **prev;
struct inode *inode;
fl_owner_t id = current->files;
struct file *f;
- int error = 0;
+ int destroy = 0, error = 0;
+ __u32 mask;
+
+ /* we use these to tell if we need to kfree */
+ new_entry = NULL;
+ dn = NULL;
+ if (!dir_notify_enable) {
+ error = -EINVAL;
+ goto out_err;
+ }
+
+ /* a 0 mask means we are explicitly removing the watch */
if ((arg & ~DN_MULTISHOT) == 0) {
dnotify_flush(filp, id);
- return 0;
+ error = 0;
+ goto out_err;
}
- if (!dir_notify_enable)
- return -EINVAL;
+
+ /* dnotify only works on directories */
inode = filp->f_path.dentry->d_inode;
- if (!S_ISDIR(inode->i_mode))
- return -ENOTDIR;
- dn = kmem_cache_alloc(dn_cache, GFP_KERNEL);
- if (dn == NULL)
- return -ENOMEM;
- spin_lock(&inode->i_lock);
- prev = &inode->i_dnotify;
- while ((odn = *prev) != NULL) {
- if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
- odn->dn_fd = fd;
- odn->dn_mask |= arg;
- inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
- goto out_free;
- }
- prev = &odn->dn_next;
+ if (!S_ISDIR(inode->i_mode)) {
+ error = -ENOTDIR;
+ goto out_err;
}
- rcu_read_lock();
- f = fcheck(fd);
- rcu_read_unlock();
- /* we'd lost the race with close(), sod off silently */
- /* note that inode->i_lock prevents reordering problems
- * between accesses to descriptor table and ->i_dnotify */
- if (f != filp)
- goto out_free;
+ /* expect most fcntl to add new rather than augment old */
+ dn = kmem_cache_alloc(dnotify_struct_cache, GFP_KERNEL);
+ if (!dn) {
+ error = -ENOMEM;
+ goto out_err;
+ }
- error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
- if (error)
- goto out_free;
+ /* new fsnotify mark, we expect most fcntl calls to add a new mark */
+ new_dnentry = kmem_cache_alloc(dnotify_mark_entry_cache, GFP_KERNEL);
+ if (!new_dnentry) {
+ error = -ENOMEM;
+ goto out_err;
+ }
- dn->dn_mask = arg;
- dn->dn_fd = fd;
- dn->dn_filp = filp;
- dn->dn_owner = id;
- inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
- dn->dn_next = inode->i_dnotify;
- inode->i_dnotify = dn;
- spin_unlock(&inode->i_lock);
- return 0;
+ /* convert the userspace DN_* "arg" to the internal FS_* defines in fsnotify */
+ mask = convert_arg(arg);
-out_free:
- spin_unlock(&inode->i_lock);
- kmem_cache_free(dn_cache, dn);
- return error;
-}
+ /* set up the new_entry and new_dnentry */
+ new_entry = &new_dnentry->fsn_entry;
+ fsnotify_init_mark(new_entry, dnotify_free_mark);
+ new_entry->mask = mask;
+ new_dnentry->dn = NULL;
-void __inode_dir_notify(struct inode *inode, unsigned long event)
-{
- struct dnotify_struct * dn;
- struct dnotify_struct **prev;
- struct fown_struct * fown;
- int changed = 0;
+ /* this is needed to prevent the fcntl/close race described below */
+ mutex_lock(&dnotify_mark_mutex);
+ /* add the new_entry or find an old one. */
spin_lock(&inode->i_lock);
- prev = &inode->i_dnotify;
- while ((dn = *prev) != NULL) {
- if ((dn->dn_mask & event) == 0) {
- prev = &dn->dn_next;
- continue;
- }
- fown = &dn->dn_filp->f_owner;
- send_sigio(fown, dn->dn_fd, POLL_MSG);
- if (dn->dn_mask & DN_MULTISHOT)
- prev = &dn->dn_next;
- else {
- *prev = dn->dn_next;
- changed = 1;
- kmem_cache_free(dn_cache, dn);
- }
- }
- if (changed)
- redo_inode_mask(inode);
+ entry = fsnotify_find_mark_entry(dnotify_group, inode);
spin_unlock(&inode->i_lock);
-}
-
-EXPORT_SYMBOL(__inode_dir_notify);
+ if (entry) {
+ dnentry = container_of(entry, struct dnotify_mark_entry, fsn_entry);
+ spin_lock(&entry->lock);
+ } else {
+ fsnotify_add_mark(new_entry, dnotify_group, inode);
+ spin_lock(&new_entry->lock);
+ entry = new_entry;
+ dnentry = new_dnentry;
+ /* we used new_entry, so don't free it */
+ new_entry = NULL;
+ }
-/*
- * This is hopelessly wrong, but unfixable without API changes. At
- * least it doesn't oops the kernel...
- *
- * To safely access ->d_parent we need to keep d_move away from it. Use the
- * dentry's d_lock for this.
- */
-void dnotify_parent(struct dentry *dentry, unsigned long event)
-{
- struct dentry *parent;
+ rcu_read_lock();
+ f = fcheck(fd);
+ rcu_read_unlock();
- if (!dir_notify_enable)
- return;
+ /* if (f != filp) means that we lost a race and another task/thread
+ * actually closed the fd we are still playing with before we grabbed
+ * the dnotify_mark_mutex and entry->lock. Since closing the fd is the
+ * only time we clean up the mark entries we need to get our mark off
+ * the list. */
+ if (f != filp) {
+ /* if we added ourselves, shoot ourselves, it's possible that
+ * the flush actually did shoot this entry. That's fine too
+ * since multiple calls to destroy_mark is perfectly safe, if
+ * we found a dnentry already attached to the inode, just sod
+ * off silently as the flush at close time dealt with it.
+ */
+ if (dnentry == new_dnentry)
+ destroy = 1;
+ goto out;
+ }
- spin_lock(&dentry->d_lock);
- parent = dentry->d_parent;
- if (parent->d_inode->i_dnotify_mask & event) {
- dget(parent);
- spin_unlock(&dentry->d_lock);
- __inode_dir_notify(parent->d_inode, event);
- dput(parent);
- } else {
- spin_unlock(&dentry->d_lock);
+ error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
+ if (error) {
+ /* if we added, we must shoot */
+ if (dnentry == new_dnentry)
+ destroy = 1;
+ goto out;
}
+
+ error = attach_dn(dn, dnentry, id, fd, filp, mask);
+ /* !error means that we attached the dn to the dnentry, so don't free it */
+ if (!error)
+ dn = NULL;
+ /* -EEXIST means that we didn't add this new dn and used an old one.
+ * that isn't an error (and the unused dn should be freed) */
+ else if (error == -EEXIST)
+ error = 0;
+
+ dnotify_recalc_inode_mask(entry);
+out:
+ spin_unlock(&entry->lock);
+
+ if (destroy)
+ fsnotify_destroy_mark_by_entry(entry);
+
+ fsnotify_recalc_group_mask(dnotify_group);
+
+ mutex_unlock(&dnotify_mark_mutex);
+ fsnotify_put_mark(entry);
+out_err:
+ if (new_entry)
+ fsnotify_put_mark(new_entry);
+ if (dn)
+ kmem_cache_free(dnotify_struct_cache, dn);
+ return error;
}
-EXPORT_SYMBOL_GPL(dnotify_parent);
static int __init dnotify_init(void)
{
- dn_cache = kmem_cache_create("dnotify_cache",
- sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL);
+ dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC);
+ dnotify_mark_entry_cache = KMEM_CACHE(dnotify_mark_entry, SLAB_PANIC);
+
+ dnotify_group = fsnotify_obtain_group(DNOTIFY_GROUP_NUM,
+ 0, &dnotify_fsnotify_ops);
+ if (IS_ERR(dnotify_group))
+ panic("unable to allocate fsnotify group for dnotify\n");
return 0;
}
__u32 new_dir_mask = 0;
if (old_dir == new_dir) {
- inode_dir_notify(old_dir, DN_RENAME);
old_dir_mask = FS_DN_RENAME;
- } else {
- inode_dir_notify(old_dir, DN_DELETE);
- old_dir_mask = FS_DELETE;
- inode_dir_notify(new_dir, DN_CREATE);
- new_dir_mask = FS_CREATE;
}
if (isdir) {
if (isdir)
mask |= FS_IN_ISDIR;
- dnotify_parent(dentry, DN_DELETE);
fsnotify_parent(dentry, mask);
}
*/
static inline void fsnotify_create(struct inode *inode, struct dentry *dentry)
{
- inode_dir_notify(inode, DN_CREATE);
inotify_inode_queue_event(inode, IN_CREATE, 0, dentry->d_name.name,
dentry->d_inode);
audit_inode_child(dentry->d_name.name, dentry, inode);
*/
static inline void fsnotify_link(struct inode *dir, struct inode *inode, struct dentry *new_dentry)
{
- inode_dir_notify(dir, DN_CREATE);
inotify_inode_queue_event(dir, IN_CREATE, 0, new_dentry->d_name.name,
inode);
fsnotify_link_count(inode);
__u32 mask = (FS_CREATE | FS_IN_ISDIR);
struct inode *d_inode = dentry->d_inode;
- inode_dir_notify(inode, DN_CREATE);
inotify_inode_queue_event(inode, mask, 0, dentry->d_name.name, d_inode);
audit_inode_child(dentry->d_name.name, dentry, inode);
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
- dnotify_parent(dentry, DN_ACCESS);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
fsnotify_parent(dentry, mask);
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
- dnotify_parent(dentry, DN_MODIFY);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
fsnotify_parent(dentry, mask);
static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
{
struct inode *inode = dentry->d_inode;
- int dn_mask = 0;
- __u32 in_mask = 0;
+ __u32 mask = 0;
+
+ if (ia_valid & ATTR_UID)
+ mask |= FS_ATTRIB;
+ if (ia_valid & ATTR_GID)
+ mask |= FS_ATTRIB;
+ if (ia_valid & ATTR_SIZE)
+ mask |= FS_MODIFY;
- if (ia_valid & ATTR_UID) {
- in_mask |= FS_ATTRIB;
- dn_mask |= DN_ATTRIB;
- }
- if (ia_valid & ATTR_GID) {
- in_mask |= FS_ATTRIB;
- dn_mask |= DN_ATTRIB;
- }
- if (ia_valid & ATTR_SIZE) {
- in_mask |= FS_MODIFY;
- dn_mask |= DN_MODIFY;
- }
/* both times implies a utime(s) call */
if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
- {
- in_mask |= FS_ATTRIB;
- dn_mask |= DN_ATTRIB;
- } else if (ia_valid & ATTR_ATIME) {
- in_mask |= FS_ACCESS;
- dn_mask |= DN_ACCESS;
- } else if (ia_valid & ATTR_MTIME) {
- in_mask |= FS_MODIFY;
- dn_mask |= DN_MODIFY;
- }
- if (ia_valid & ATTR_MODE) {
- in_mask |= FS_ATTRIB;
- dn_mask |= DN_ATTRIB;
- }
+ mask |= FS_ATTRIB;
+ else if (ia_valid & ATTR_ATIME)
+ mask |= FS_ACCESS;
+ else if (ia_valid & ATTR_MTIME)
+ mask |= FS_MODIFY;
+
+ if (ia_valid & ATTR_MODE)
+ mask |= FS_ATTRIB;
- if (dn_mask)
- dnotify_parent(dentry, dn_mask);
- if (in_mask) {
+ if (mask) {
if (S_ISDIR(inode->i_mode))
- in_mask |= FS_IN_ISDIR;
- inotify_inode_queue_event(inode, in_mask, 0, NULL, NULL);
+ mask |= FS_IN_ISDIR;
+ inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
- fsnotify_parent(dentry, in_mask);
- fsnotify(inode, in_mask, inode, FSNOTIFY_EVENT_INODE);
+ fsnotify_parent(dentry, mask);
+ fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
}
}
projects / openwrt / staging / blogic.git / commitdiff