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linux/fs/ceph/mds_client.h
Alex Elder d8fb02abdc ceph: create a new session lock to avoid lock inversion 
Lockdep was reporting a possible circular lock dependency in
dentry_lease_is_valid().  That function needs to sample the
session's s_cap_gen and and s_cap_ttl fields coherently, but needs
to do so while holding a dentry lock.  The s_cap_lock field was
being used to protect the two fields, but that can't be taken while
holding a lock on a dentry within the session.

In most cases, the s_cap_gen and s_cap_ttl fields only get operated
on separately.  But in three cases they need to be updated together.
Implement a new lock to protect the spots updating both fields
atomically is required.

Signed-off-by: Alex Elder <elder@dreamhost.com>
Reviewed-by: Sage Weil <sage@newdream.net>
2012-02-02 12:49:19 -08:00

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#ifndef _FS_CEPH_MDS_CLIENT_H
#define _FS_CEPH_MDS_CLIENT_H
#include <linux/completion.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <linux/ceph/types.h>
#include <linux/ceph/messenger.h>
#include <linux/ceph/mdsmap.h>
/*
* Some lock dependencies:
*
* session->s_mutex
* mdsc->mutex
*
* mdsc->snap_rwsem
*
* ci->i_ceph_lock
* mdsc->snap_flush_lock
* mdsc->cap_delay_lock
*
*/
struct ceph_fs_client;
struct ceph_cap;
/*
* parsed info about a single inode. pointers are into the encoded
* on-wire structures within the mds reply message payload.
*/
struct ceph_mds_reply_info_in {
struct ceph_mds_reply_inode *in;
struct ceph_dir_layout dir_layout;
u32 symlink_len;
char *symlink;
u32 xattr_len;
char *xattr_data;
};
/*
* parsed info about an mds reply, including information about
* either: 1) the target inode and/or its parent directory and dentry,
* and directory contents (for readdir results), or
* 2) the file range lock info (for fcntl F_GETLK results).
*/
struct ceph_mds_reply_info_parsed {
struct ceph_mds_reply_head *head;
/* trace */
struct ceph_mds_reply_info_in diri, targeti;
struct ceph_mds_reply_dirfrag *dirfrag;
char *dname;
u32 dname_len;
struct ceph_mds_reply_lease *dlease;
/* extra */
union {
/* for fcntl F_GETLK results */
struct ceph_filelock *filelock_reply;
/* for readdir results */
struct {
struct ceph_mds_reply_dirfrag *dir_dir;
int dir_nr;
char **dir_dname;
u32 *dir_dname_len;
struct ceph_mds_reply_lease **dir_dlease;
struct ceph_mds_reply_info_in *dir_in;
u8 dir_complete, dir_end;
};
};
/* encoded blob describing snapshot contexts for certain
operations (e.g., open) */
void *snapblob;
int snapblob_len;
};
/*
* cap releases are batched and sent to the MDS en masse.
*/
#define CEPH_CAPS_PER_RELEASE ((PAGE_CACHE_SIZE - \
sizeof(struct ceph_mds_cap_release)) / \
sizeof(struct ceph_mds_cap_item))
/*
* state associated with each MDS<->client session
*/
enum {
CEPH_MDS_SESSION_NEW = 1,
CEPH_MDS_SESSION_OPENING = 2,
CEPH_MDS_SESSION_OPEN = 3,
CEPH_MDS_SESSION_HUNG = 4,
CEPH_MDS_SESSION_CLOSING = 5,
CEPH_MDS_SESSION_RESTARTING = 6,
CEPH_MDS_SESSION_RECONNECTING = 7,
};
struct ceph_mds_session {
struct ceph_mds_client *s_mdsc;
int s_mds;
int s_state;
unsigned long s_ttl; /* time until mds kills us */
u64 s_seq; /* incoming msg seq # */
struct mutex s_mutex; /* serialize session messages */
struct ceph_connection s_con;
struct ceph_authorizer *s_authorizer;
void *s_authorizer_buf, *s_authorizer_reply_buf;
size_t s_authorizer_buf_len, s_authorizer_reply_buf_len;
/* protected by s_gen_ttl_lock */
spinlock_t s_gen_ttl_lock;
u32 s_cap_gen; /* inc each time we get mds stale msg */
unsigned long s_cap_ttl; /* when session caps expire */
/* protected by s_cap_lock */
spinlock_t s_cap_lock;
struct list_head s_caps; /* all caps issued by this session */
int s_nr_caps, s_trim_caps;
int s_num_cap_releases;
struct list_head s_cap_releases; /* waiting cap_release messages */
struct list_head s_cap_releases_done; /* ready to send */
struct ceph_cap *s_cap_iterator;
/* protected by mutex */
struct list_head s_cap_flushing; /* inodes w/ flushing caps */
struct list_head s_cap_snaps_flushing;
unsigned long s_renew_requested; /* last time we sent a renew req */
u64 s_renew_seq;
atomic_t s_ref;
struct list_head s_waiting; /* waiting requests */
struct list_head s_unsafe; /* unsafe requests */
};
/*
* modes of choosing which MDS to send a request to
*/
enum {
USE_ANY_MDS,
USE_RANDOM_MDS,
USE_AUTH_MDS, /* prefer authoritative mds for this metadata item */
};
struct ceph_mds_request;
struct ceph_mds_client;
/*
* request completion callback
*/
typedef void (*ceph_mds_request_callback_t) (struct ceph_mds_client *mdsc,
struct ceph_mds_request *req);
/*
* an in-flight mds request
*/
struct ceph_mds_request {
u64 r_tid; /* transaction id */
struct rb_node r_node;
struct ceph_mds_client *r_mdsc;
int r_op; /* mds op code */
/* operation on what? */
struct inode *r_inode; /* arg1 */
struct dentry *r_dentry; /* arg1 */
struct dentry *r_old_dentry; /* arg2: rename from or link from */
struct inode *r_old_dentry_dir; /* arg2: old dentry's parent dir */
char *r_path1, *r_path2;
struct ceph_vino r_ino1, r_ino2;
struct inode *r_locked_dir; /* dir (if any) i_mutex locked by vfs */
struct inode *r_target_inode; /* resulting inode */
struct mutex r_fill_mutex;
union ceph_mds_request_args r_args;
int r_fmode; /* file mode, if expecting cap */
uid_t r_uid;
gid_t r_gid;
/* for choosing which mds to send this request to */
int r_direct_mode;
u32 r_direct_hash; /* choose dir frag based on this dentry hash */
bool r_direct_is_hash; /* true if r_direct_hash is valid */
/* data payload is used for xattr ops */
struct page **r_pages;
int r_num_pages;
int r_data_len;
/* what caps shall we drop? */
int r_inode_drop, r_inode_unless;
int r_dentry_drop, r_dentry_unless;
int r_old_dentry_drop, r_old_dentry_unless;
struct inode *r_old_inode;
int r_old_inode_drop, r_old_inode_unless;
struct ceph_msg *r_request; /* original request */
int r_request_release_offset;
struct ceph_msg *r_reply;
struct ceph_mds_reply_info_parsed r_reply_info;
int r_err;
bool r_aborted;
unsigned long r_timeout; /* optional. jiffies */
unsigned long r_started; /* start time to measure timeout against */
unsigned long r_request_started; /* start time for mds request only,
used to measure lease durations */
/* link unsafe requests to parent directory, for fsync */
struct inode *r_unsafe_dir;
struct list_head r_unsafe_dir_item;
struct ceph_mds_session *r_session;
int r_attempts; /* resend attempts */
int r_num_fwd; /* number of forward attempts */
int r_resend_mds; /* mds to resend to next, if any*/
u32 r_sent_on_mseq; /* cap mseq request was sent at*/
struct kref r_kref;
struct list_head r_wait;
struct completion r_completion;
struct completion r_safe_completion;
ceph_mds_request_callback_t r_callback;
struct list_head r_unsafe_item; /* per-session unsafe list item */
bool r_got_unsafe, r_got_safe, r_got_result;
bool r_did_prepopulate;
u32 r_readdir_offset;
struct ceph_cap_reservation r_caps_reservation;
int r_num_caps;
};
/*
* mds client state
*/
struct ceph_mds_client {
struct ceph_fs_client *fsc;
struct mutex mutex; /* all nested structures */
struct ceph_mdsmap *mdsmap;
struct completion safe_umount_waiters;
wait_queue_head_t session_close_wq;
struct list_head waiting_for_map;
struct ceph_mds_session **sessions; /* NULL for mds if no session */
int max_sessions; /* len of s_mds_sessions */
int stopping; /* true if shutting down */
/*
* snap_rwsem will cover cap linkage into snaprealms, and
* realm snap contexts. (later, we can do per-realm snap
* contexts locks..) the empty list contains realms with no
* references (implying they contain no inodes with caps) that
* should be destroyed.
*/
struct rw_semaphore snap_rwsem;
struct rb_root snap_realms;
struct list_head snap_empty;
spinlock_t snap_empty_lock; /* protect snap_empty */
u64 last_tid; /* most recent mds request */
struct rb_root request_tree; /* pending mds requests */
struct delayed_work delayed_work; /* delayed work */
unsigned long last_renew_caps; /* last time we renewed our caps */
struct list_head cap_delay_list; /* caps with delayed release */
spinlock_t cap_delay_lock; /* protects cap_delay_list */
struct list_head snap_flush_list; /* cap_snaps ready to flush */
spinlock_t snap_flush_lock;
u64 cap_flush_seq;
struct list_head cap_dirty; /* inodes with dirty caps */
struct list_head cap_dirty_migrating; /* ...that are migration... */
int num_cap_flushing; /* # caps we are flushing */
spinlock_t cap_dirty_lock; /* protects above items */
wait_queue_head_t cap_flushing_wq;
/*
* Cap reservations
*
* Maintain a global pool of preallocated struct ceph_caps, referenced
* by struct ceph_caps_reservations. This ensures that we preallocate
* memory needed to successfully process an MDS response. (If an MDS
* sends us cap information and we fail to process it, we will have
* problems due to the client and MDS being out of sync.)
*
* Reservations are 'owned' by a ceph_cap_reservation context.
*/
spinlock_t caps_list_lock;
struct list_head caps_list; /* unused (reserved or
unreserved) */
int caps_total_count; /* total caps allocated */
int caps_use_count; /* in use */
int caps_reserve_count; /* unused, reserved */
int caps_avail_count; /* unused, unreserved */
int caps_min_count; /* keep at least this many
(unreserved) */
spinlock_t dentry_lru_lock;
struct list_head dentry_lru;
int num_dentry;
};
extern const char *ceph_mds_op_name(int op);
extern struct ceph_mds_session *
__ceph_lookup_mds_session(struct ceph_mds_client *, int mds);
static inline struct ceph_mds_session *
ceph_get_mds_session(struct ceph_mds_session *s)
{
atomic_inc(&s->s_ref);
return s;
}
extern void ceph_put_mds_session(struct ceph_mds_session *s);
extern int ceph_send_msg_mds(struct ceph_mds_client *mdsc,
struct ceph_msg *msg, int mds);
extern int ceph_mdsc_init(struct ceph_fs_client *fsc);
extern void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc);
extern void ceph_mdsc_destroy(struct ceph_fs_client *fsc);
extern void ceph_mdsc_sync(struct ceph_mds_client *mdsc);
extern void ceph_mdsc_lease_release(struct ceph_mds_client *mdsc,
struct inode *inode,
struct dentry *dn);
extern void ceph_invalidate_dir_request(struct ceph_mds_request *req);
extern struct ceph_mds_request *
ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode);
extern void ceph_mdsc_submit_request(struct ceph_mds_client *mdsc,
struct ceph_mds_request *req);
extern int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
struct inode *dir,
struct ceph_mds_request *req);
static inline void ceph_mdsc_get_request(struct ceph_mds_request *req)
{
kref_get(&req->r_kref);
}
extern void ceph_mdsc_release_request(struct kref *kref);
static inline void ceph_mdsc_put_request(struct ceph_mds_request *req)
{
kref_put(&req->r_kref, ceph_mdsc_release_request);
}
extern int ceph_add_cap_releases(struct ceph_mds_client *mdsc,
struct ceph_mds_session *session);
extern void ceph_send_cap_releases(struct ceph_mds_client *mdsc,
struct ceph_mds_session *session);
extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc);
extern char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *base,
int stop_on_nosnap);
extern void __ceph_mdsc_drop_dentry_lease(struct dentry *dentry);
extern void ceph_mdsc_lease_send_msg(struct ceph_mds_session *session,
struct inode *inode,
struct dentry *dentry, char action,
u32 seq);
extern void ceph_mdsc_handle_map(struct ceph_mds_client *mdsc,
struct ceph_msg *msg);
extern void ceph_mdsc_open_export_target_sessions(struct ceph_mds_client *mdsc,
struct ceph_mds_session *session);
#endif
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