35e481761c
Inotify instance is destroyed when all references to it are dropped. That not only means that the corresponding file descriptor needs to be closed but also that all corresponding instance marks are freed (as each mark holds a reference to the inotify instance). However marks are freed only after SRCU period ends which can take some time and thus if user rapidly creates and frees inotify instances, number of existing inotify instances can exceed max_user_instances limit although from user point of view there is always at most one existing instance. Thus inotify_init() returns EMFILE error which is hard to justify from user point of view. This problem is exposed by LTP inotify06 testcase on some machines. We fix the problem by making sure all group marks are properly freed while destroying inotify instance. We wait for SRCU period to end in that path anyway since we have to make sure there is no event being added to the instance while we are tearing down the instance. So it takes only some plumbing to allow for marks to be destroyed in that path as well and not from a dedicated work item. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com> Tested-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
77 lines
3 KiB
C
77 lines
3 KiB
C
#ifndef __FS_NOTIFY_FSNOTIFY_H_
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#define __FS_NOTIFY_FSNOTIFY_H_
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#include <linux/list.h>
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#include <linux/fsnotify.h>
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#include <linux/srcu.h>
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#include <linux/types.h>
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#include "../mount.h"
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/* destroy all events sitting in this groups notification queue */
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extern void fsnotify_flush_notify(struct fsnotify_group *group);
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/* protects reads of inode and vfsmount marks list */
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extern struct srcu_struct fsnotify_mark_srcu;
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/* Calculate mask of events for a list of marks */
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extern u32 fsnotify_recalc_mask(struct hlist_head *head);
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/* compare two groups for sorting of marks lists */
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extern int fsnotify_compare_groups(struct fsnotify_group *a,
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struct fsnotify_group *b);
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extern void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *fsn_mark,
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__u32 mask);
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/* Add mark to a proper place in mark list */
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extern int fsnotify_add_mark_list(struct hlist_head *head,
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struct fsnotify_mark *mark,
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int allow_dups);
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/* add a mark to an inode */
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extern int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
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struct fsnotify_group *group, struct inode *inode,
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int allow_dups);
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/* add a mark to a vfsmount */
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extern int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
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struct fsnotify_group *group, struct vfsmount *mnt,
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int allow_dups);
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/* vfsmount specific destruction of a mark */
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extern void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark);
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/* inode specific destruction of a mark */
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extern void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark);
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/* Find mark belonging to given group in the list of marks */
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extern struct fsnotify_mark *fsnotify_find_mark(struct hlist_head *head,
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struct fsnotify_group *group);
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/* Destroy all marks in the given list protected by 'lock' */
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extern void fsnotify_destroy_marks(struct hlist_head *head, spinlock_t *lock);
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/* run the list of all marks associated with inode and destroy them */
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static inline void fsnotify_clear_marks_by_inode(struct inode *inode)
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{
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fsnotify_destroy_marks(&inode->i_fsnotify_marks, &inode->i_lock);
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}
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/* run the list of all marks associated with vfsmount and destroy them */
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static inline void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
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{
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fsnotify_destroy_marks(&real_mount(mnt)->mnt_fsnotify_marks,
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&mnt->mnt_root->d_lock);
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}
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/* prepare for freeing all marks associated with given group */
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extern void fsnotify_detach_group_marks(struct fsnotify_group *group);
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/*
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* wait for fsnotify_mark_srcu period to end and free all marks in destroy_list
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*/
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extern void fsnotify_mark_destroy_list(void);
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/*
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* update the dentry->d_flags of all of inode's children to indicate if inode cares
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* about events that happen to its children.
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*/
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extern void __fsnotify_update_child_dentry_flags(struct inode *inode);
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/* allocate and destroy and event holder to attach events to notification/access queues */
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extern struct fsnotify_event_holder *fsnotify_alloc_event_holder(void);
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extern void fsnotify_destroy_event_holder(struct fsnotify_event_holder *holder);
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#endif /* __FS_NOTIFY_FSNOTIFY_H_ */
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