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17d912d54f
Being a module parameter, it's possible to do:
# modprobe cifs drop_dir_cache=1
Which will lead to a crash, because cifs_tcp_ses_list hasn't been
initialized yet:
[ 168.242624] BUG: kernel NULL pointer dereference, address: 0000000000000010
[ 168.242952] #PF: supervisor read access in kernel mode
[ 168.243175] #PF: error_code(0x0000) - not-present page
[ 168.243394] PGD 0 P4D 0
[ 168.243524] Oops: Oops: 0000 [#1] SMP NOPTI
[ 168.243703] CPU: 2 UID: 0 PID: 1105 Comm: modprobe Not tainted 7.0.0-lku #5 PREEMPT(lazy)
[ 168.244054] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-2-g4f253b9b-prebuilt.qemu.org 04/01/2014
[ 168.244557] RIP: 0010:cifs_param_set_drop_dir_cache+0x7c/0x100 [cifs]
...
[ 168.248785] Call Trace:
[ 168.248915] <TASK>
[ 168.249023] parse_args+0x285/0x3a0
[ 168.249204] ? __pfx_unknown_module_param_cb+0x10/0x10
[ 168.249448] load_module+0x192b/0x1bb0
[ 168.249637] ? __pfx_unknown_module_param_cb+0x10/0x10
[ 168.249882] ? kernel_read_file+0x27d/0x2b0
[ 168.250088] init_module_from_file+0xce/0xf0
[ 168.250291] idempotent_init_module+0xfb/0x2f0
[ 168.250496] __x64_sys_finit_module+0x5a/0xa0
[ 168.250694] do_syscall_64+0xe0/0x5a0
[ 168.250863] ? exc_page_fault+0x65/0x160
[ 168.251050] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 168.251284] RIP: 0033:0x7fcaa12b774d
Instead of fixing this with some kind of "is module initialized"
approach, this patch instead moves that functionality to procfs,
setting a write op for the existing open_dirs entry, where
writing a 0 to it will drop the cached directory entries.
Also make it available only when CONFIG_CIFS_DEBUG=y.
A small change needed now is to not call flush_delayed_work()
on invalidate_all_cached_dirs() when called from procfs (can't sleep in
that context).
So add a @sync arg to invalidate_all_cached_dirs() to control when to
flush the delayed works.
Fixes: dde6667fa3 ("smb: client: add drop_dir_cache module parameter to invalidate cached dirents")
Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>
97 lines
2.7 KiB
C
97 lines
2.7 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 file *file; /*
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* Used to associate the cache with a single
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* open file instance.
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*/
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struct mutex de_mutex;
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loff_t pos; /* Expected ctx->pos */
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struct list_head entries;
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/* accounting for cached entries in this directory */
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unsigned long entries_count;
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unsigned long bytes_used;
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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;
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bool is_open;
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bool on_list;
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bool file_all_info_is_valid;
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unsigned long time; /* jiffies of when lease was taken */
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unsigned long last_access_time; /* jiffies of when last accessed */
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struct kref refcount;
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struct cifs_fid fid;
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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 cached_dirents dirents;
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/* Must be last as it ends in a flexible-array member. */
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struct smb2_file_all_info file_all_info;
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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 delayed_work laundromat_work;
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/* aggregate accounting for all cached dirents under this tcon */
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atomic_long_t total_dirents_entries;
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atomic64_t total_dirents_bytes;
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};
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/* Module-wide directory cache accounting (defined in cifsfs.c) */
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extern atomic64_t cifs_dircache_bytes_used; /* bytes across all mounts */
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static inline bool
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is_valid_cached_dir(struct cached_fid *cfid)
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{
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return cfid->time && cfid->has_lease;
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}
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struct cached_fids *init_cached_dirs(void);
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void free_cached_dirs(struct cached_fids *cfids);
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int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon, const char *path,
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struct cifs_sb_info *cifs_sb, bool lookup_only,
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struct cached_fid **ret_cfid);
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int open_cached_dir_by_dentry(struct cifs_tcon *tcon, struct dentry *dentry,
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struct cached_fid **ret_cfid);
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void close_cached_dir(struct cached_fid *cfid);
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void drop_cached_dir_by_name(const unsigned int xid, struct cifs_tcon *tcon,
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const char *name, struct cifs_sb_info *cifs_sb);
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void close_all_cached_dirs(struct cifs_sb_info *cifs_sb);
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void invalidate_all_cached_dirs(struct cifs_tcon *tcon, bool sync);
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bool cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16]);
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#endif /* _CACHED_DIR_H */
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