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3fa640d035
The unmount process (cifs_kill_sb() calling close_all_cached_dirs()) can
race with various cached directory operations, which ultimately results
in dentries not being dropped and these kernel BUGs:
BUG: Dentry ffff88814f37e358{i=1000000000080,n=/} still in use (2) [unmount of cifs cifs]
VFS: Busy inodes after unmount of cifs (cifs)
------------[ cut here ]------------
kernel BUG at fs/super.c:661!
This happens when a cfid is in the process of being cleaned up when, and
has been removed from the cfids->entries list, including:
- Receiving a lease break from the server
- Server reconnection triggers invalidate_all_cached_dirs(), which
removes all the cfids from the list
- The laundromat thread decides to expire an old cfid.
To solve these problems, dropping the dentry is done in queued work done
in a newly-added cfid_put_wq workqueue, and close_all_cached_dirs()
flushes that workqueue after it drops all the dentries of which it's
aware. This is a global workqueue (rather than scoped to a mount), but
the queued work is minimal.
The final cleanup work for cleaning up a cfid is performed via work
queued in the serverclose_wq workqueue; this is done separate from
dropping the dentries so that close_all_cached_dirs() doesn't block on
any server operations.
Both of these queued works expect to invoked with a cfid reference and
a tcon reference to avoid those objects from being freed while the work
is ongoing.
While we're here, add proper locking to close_all_cached_dirs(), and
locking around the freeing of cfid->dentry.
Fixes: ebe98f1447 ("cifs: enable caching of directories for which a lease is held")
Cc: stable@vger.kernel.org
Signed-off-by: Paul Aurich <paul@darkrain42.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Functions to handle the cached directory entries
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*
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* Copyright (c) 2022, Ronnie Sahlberg <lsahlber@redhat.com>
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*/
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#ifndef _CACHED_DIR_H
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#define _CACHED_DIR_H
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struct cached_dirent {
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struct list_head entry;
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char *name;
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int namelen;
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loff_t pos;
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struct cifs_fattr fattr;
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};
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struct cached_dirents {
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bool is_valid:1;
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bool is_failed:1;
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struct dir_context *ctx; /*
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* Only used to make sure we only take entries
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* from a single context. Never dereferenced.
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*/
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struct mutex de_mutex;
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int pos; /* Expected ctx->pos */
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struct list_head entries;
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};
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struct cached_fid {
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struct list_head entry;
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struct cached_fids *cfids;
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const char *path;
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bool has_lease:1;
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bool is_open:1;
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bool on_list:1;
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bool file_all_info_is_valid:1;
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unsigned long time; /* jiffies of when lease was taken */
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struct kref refcount;
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struct cifs_fid fid;
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spinlock_t fid_lock;
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struct cifs_tcon *tcon;
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struct dentry *dentry;
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struct work_struct put_work;
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struct work_struct close_work;
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struct smb2_file_all_info file_all_info;
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struct cached_dirents dirents;
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};
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/* default MAX_CACHED_FIDS is 16 */
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struct cached_fids {
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/* Must be held when:
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* - accessing the cfids->entries list
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* - accessing the cfids->dying list
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*/
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spinlock_t cfid_list_lock;
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int num_entries;
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struct list_head entries;
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struct list_head dying;
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struct work_struct invalidation_work;
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struct delayed_work laundromat_work;
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};
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extern struct cached_fids *init_cached_dirs(void);
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extern void free_cached_dirs(struct cached_fids *cfids);
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extern int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
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const char *path,
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struct cifs_sb_info *cifs_sb,
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bool lookup_only, struct cached_fid **cfid);
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extern int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
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struct dentry *dentry,
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struct cached_fid **cfid);
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extern void close_cached_dir(struct cached_fid *cfid);
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extern void drop_cached_dir_by_name(const unsigned int xid,
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struct cifs_tcon *tcon,
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const char *name,
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struct cifs_sb_info *cifs_sb);
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extern void close_all_cached_dirs(struct cifs_sb_info *cifs_sb);
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extern void invalidate_all_cached_dirs(struct cifs_tcon *tcon);
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extern int cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16]);
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#endif /* _CACHED_DIR_H */
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