forked from luck/tmp_suning_uos_patched
inotify: seperate new watch creation updating existing watches
There is nothing known wrong with the inotify watch addition/modification but this patch seperates the two code paths to make them each easy to verify as correct. Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric Paris
parent
1e23502cc5
commit
52cef7555a
|
|
@ -431,80 +431,29 @@ static void inotify_free_mark(struct fsnotify_mark_entry *entry)
|
|||
kmem_cache_free(inotify_inode_mark_cachep, ientry);
|
||||
}
|
||||
|
||||
static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
|
||||
static int inotify_update_existing_watch(struct fsnotify_group *group,
|
||||
struct inode *inode,
|
||||
u32 arg)
|
||||
{
|
||||
struct fsnotify_mark_entry *entry = NULL;
|
||||
struct fsnotify_mark_entry *entry;
|
||||
struct inotify_inode_mark_entry *ientry;
|
||||
struct inotify_inode_mark_entry *tmp_ientry;
|
||||
int ret = 0;
|
||||
int add = (arg & IN_MASK_ADD);
|
||||
__u32 mask;
|
||||
__u32 old_mask, new_mask;
|
||||
__u32 mask;
|
||||
int add = (arg & IN_MASK_ADD);
|
||||
int ret;
|
||||
|
||||
/* don't allow invalid bits: we don't want flags set */
|
||||
mask = inotify_arg_to_mask(arg);
|
||||
if (unlikely(!mask))
|
||||
return -EINVAL;
|
||||
|
||||
tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
|
||||
if (unlikely(!tmp_ientry))
|
||||
return -ENOMEM;
|
||||
/* we set the mask at the end after attaching it */
|
||||
fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark);
|
||||
tmp_ientry->wd = -1;
|
||||
|
||||
find_entry:
|
||||
spin_lock(&inode->i_lock);
|
||||
entry = fsnotify_find_mark_entry(group, inode);
|
||||
spin_unlock(&inode->i_lock);
|
||||
if (entry) {
|
||||
ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
|
||||
} else {
|
||||
ret = -ENOSPC;
|
||||
if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
|
||||
goto out_err;
|
||||
retry:
|
||||
ret = -ENOMEM;
|
||||
if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL)))
|
||||
goto out_err;
|
||||
if (!entry)
|
||||
return -ENOENT;
|
||||
|
||||
spin_lock(&group->inotify_data.idr_lock);
|
||||
ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry,
|
||||
group->inotify_data.last_wd,
|
||||
&tmp_ientry->wd);
|
||||
spin_unlock(&group->inotify_data.idr_lock);
|
||||
if (ret) {
|
||||
if (ret == -EAGAIN)
|
||||
goto retry;
|
||||
goto out_err;
|
||||
}
|
||||
|
||||
ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode);
|
||||
if (ret) {
|
||||
inotify_remove_from_idr(group, tmp_ientry);
|
||||
if (ret == -EEXIST)
|
||||
goto find_entry;
|
||||
goto out_err;
|
||||
}
|
||||
|
||||
/* tmp_ientry has been added to the inode, so we are all set up.
|
||||
* now we just need to make sure tmp_ientry doesn't get freed and
|
||||
* we need to set up entry and ientry so the generic code can
|
||||
* do its thing. */
|
||||
ientry = tmp_ientry;
|
||||
entry = &ientry->fsn_entry;
|
||||
tmp_ientry = NULL;
|
||||
|
||||
atomic_inc(&group->inotify_data.user->inotify_watches);
|
||||
|
||||
/* update the idr hint */
|
||||
group->inotify_data.last_wd = ientry->wd;
|
||||
|
||||
/* we put the mark on the idr, take a reference */
|
||||
fsnotify_get_mark(entry);
|
||||
}
|
||||
|
||||
ret = ientry->wd;
|
||||
ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
|
||||
|
||||
spin_lock(&entry->lock);
|
||||
|
||||
|
|
@ -536,19 +485,104 @@ static int inotify_update_watch(struct fsnotify_group *group, struct inode *inod
|
|||
fsnotify_recalc_group_mask(group);
|
||||
}
|
||||
|
||||
/* this either matches fsnotify_find_mark_entry, or init_mark_entry
|
||||
* depending on which path we took... */
|
||||
/* return the wd */
|
||||
ret = ientry->wd;
|
||||
|
||||
/* match the get from fsnotify_find_mark_entry() */
|
||||
fsnotify_put_mark(entry);
|
||||
|
||||
out_err:
|
||||
/* could be an error, could be that we found an existing mark */
|
||||
if (tmp_ientry) {
|
||||
/* on the idr but didn't make it on the inode */
|
||||
if (tmp_ientry->wd != -1)
|
||||
inotify_remove_from_idr(group, tmp_ientry);
|
||||
kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int inotify_new_watch(struct fsnotify_group *group,
|
||||
struct inode *inode,
|
||||
u32 arg)
|
||||
{
|
||||
struct inotify_inode_mark_entry *tmp_ientry;
|
||||
__u32 mask;
|
||||
int ret;
|
||||
|
||||
/* don't allow invalid bits: we don't want flags set */
|
||||
mask = inotify_arg_to_mask(arg);
|
||||
if (unlikely(!mask))
|
||||
return -EINVAL;
|
||||
|
||||
tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
|
||||
if (unlikely(!tmp_ientry))
|
||||
return -ENOMEM;
|
||||
|
||||
fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark);
|
||||
tmp_ientry->fsn_entry.mask = mask;
|
||||
tmp_ientry->wd = -1;
|
||||
|
||||
ret = -ENOSPC;
|
||||
if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
|
||||
goto out_err;
|
||||
retry:
|
||||
ret = -ENOMEM;
|
||||
if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL)))
|
||||
goto out_err;
|
||||
|
||||
spin_lock(&group->inotify_data.idr_lock);
|
||||
ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry,
|
||||
group->inotify_data.last_wd,
|
||||
&tmp_ientry->wd);
|
||||
spin_unlock(&group->inotify_data.idr_lock);
|
||||
if (ret) {
|
||||
/* idr was out of memory allocate and try again */
|
||||
if (ret == -EAGAIN)
|
||||
goto retry;
|
||||
goto out_err;
|
||||
}
|
||||
|
||||
/* we are on the idr, now get on the inode */
|
||||
ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode);
|
||||
if (ret) {
|
||||
/* we failed to get on the inode, get off the idr */
|
||||
inotify_remove_from_idr(group, tmp_ientry);
|
||||
goto out_err;
|
||||
}
|
||||
|
||||
/* we put the mark on the idr, take a reference */
|
||||
fsnotify_get_mark(&tmp_ientry->fsn_entry);
|
||||
|
||||
/* update the idr hint, who cares about races, it's just a hint */
|
||||
group->inotify_data.last_wd = tmp_ientry->wd;
|
||||
|
||||
/* increment the number of watches the user has */
|
||||
atomic_inc(&group->inotify_data.user->inotify_watches);
|
||||
|
||||
/* return the watch descriptor for this new entry */
|
||||
ret = tmp_ientry->wd;
|
||||
|
||||
/* match the ref from fsnotify_init_markentry() */
|
||||
fsnotify_put_mark(&tmp_ientry->fsn_entry);
|
||||
|
||||
out_err:
|
||||
if (ret < 0)
|
||||
kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
|
||||
{
|
||||
int ret = 0;
|
||||
|
||||
retry:
|
||||
/* try to update and existing watch with the new arg */
|
||||
ret = inotify_update_existing_watch(group, inode, arg);
|
||||
/* no mark present, try to add a new one */
|
||||
if (ret == -ENOENT)
|
||||
ret = inotify_new_watch(group, inode, arg);
|
||||
/*
|
||||
* inotify_new_watch could race with another thread which did an
|
||||
* inotify_new_watch between the update_existing and the add watch
|
||||
* here, go back and try to update an existing mark again.
|
||||
*/
|
||||
if (ret == -EEXIST)
|
||||
goto retry;
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user