From 3afca265b5f53a0b15b79531c13858049505582d Mon Sep 17 00:00:00 2001 From: Steve French Date: Thu, 22 Sep 2016 18:58:16 -0500 Subject: Clarify locking of cifs file and tcon structures and make more granular Remove the global file_list_lock to simplify cifs/smb3 locking and have spinlocks that more closely match the information they are protecting. Add new tcon->open_file_lock and file->file_info_lock spinlocks. Locks continue to follow a heirachy, cifs_socket --> cifs_ses --> cifs_tcon --> cifs_file where global tcp_ses_lock still protects socket and cifs_ses, while the the newer locks protect the lower level structure's information (tcon and cifs_file respectively). CC: Stable Signed-off-by: Steve French Signed-off-by: Pavel Shilovsky Reviewed-by: Aurelien Aptel Reviewed-by: Germano Percossi --- fs/cifs/cifsglob.h | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) (limited to 'fs/cifs/cifsglob.h') diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 8f1d8c1e72be..65f78b7a9062 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -833,6 +833,7 @@ struct cifs_tcon { struct list_head tcon_list; int tc_count; struct list_head openFileList; + spinlock_t open_file_lock; /* protects list above */ struct cifs_ses *ses; /* pointer to session associated with */ char treeName[MAX_TREE_SIZE + 1]; /* UNC name of resource in ASCII */ char *nativeFileSystem; @@ -889,7 +890,7 @@ struct cifs_tcon { #endif /* CONFIG_CIFS_STATS2 */ __u64 bytes_read; __u64 bytes_written; - spinlock_t stat_lock; + spinlock_t stat_lock; /* protects the two fields above */ #endif /* CONFIG_CIFS_STATS */ FILE_SYSTEM_DEVICE_INFO fsDevInfo; FILE_SYSTEM_ATTRIBUTE_INFO fsAttrInfo; /* ok if fs name truncated */ @@ -1040,8 +1041,10 @@ struct cifs_fid_locks { }; struct cifsFileInfo { + /* following two lists are protected by tcon->open_file_lock */ struct list_head tlist; /* pointer to next fid owned by tcon */ struct list_head flist; /* next fid (file instance) for this inode */ + /* lock list below protected by cifsi->lock_sem */ struct cifs_fid_locks *llist; /* brlocks held by this fid */ kuid_t uid; /* allows finding which FileInfo structure */ __u32 pid; /* process id who opened file */ @@ -1049,11 +1052,12 @@ struct cifsFileInfo { /* BB add lock scope info here if needed */ ; /* lock scope id (0 if none) */ struct dentry *dentry; - unsigned int f_flags; struct tcon_link *tlink; + unsigned int f_flags; bool invalidHandle:1; /* file closed via session abend */ bool oplock_break_cancelled:1; - int count; /* refcount protected by cifs_file_list_lock */ + int count; + spinlock_t file_info_lock; /* protects four flag/count fields above */ struct mutex fh_mutex; /* prevents reopen race after dead ses*/ struct cifs_search_info srch_inf; struct work_struct oplock_break; /* work for oplock breaks */ @@ -1120,7 +1124,7 @@ struct cifs_writedata { /* * Take a reference on the file private data. Must be called with - * cifs_file_list_lock held. + * cfile->file_info_lock held. */ static inline void cifsFileInfo_get_locked(struct cifsFileInfo *cifs_file) @@ -1514,8 +1518,10 @@ require use of the stronger protocol */ * GlobalMid_Lock protects: * list operations on pending_mid_q and oplockQ * updates to XID counters, multiplex id and SMB sequence numbers - * cifs_file_list_lock protects: - * list operations on tcp and SMB session lists and tCon lists + * tcp_ses_lock protects: + * list operations on tcp and SMB session lists + * tcon->open_file_lock protects the list of open files hanging off the tcon + * cfile->file_info_lock protects counters and fields in cifs file struct * f_owner.lock protects certain per file struct operations * mapping->page_lock protects certain per page operations * @@ -1547,18 +1553,12 @@ GLOBAL_EXTERN struct list_head cifs_tcp_ses_list; * tcp session, and the list of tcon's per smb session. It also protects * the reference counters for the server, smb session, and tcon. Finally, * changes to the tcon->tidStatus should be done while holding this lock. + * generally the locks should be taken in order tcp_ses_lock before + * tcon->open_file_lock and that before file->file_info_lock since the + * structure order is cifs_socket-->cifs_ses-->cifs_tcon-->cifs_file */ GLOBAL_EXTERN spinlock_t cifs_tcp_ses_lock; -/* - * This lock protects the cifs_file->llist and cifs_file->flist - * list operations, and updates to some flags (cifs_file->invalidHandle) - * It will be moved to either use the tcon->stat_lock or equivalent later. - * If cifs_tcp_ses_lock and the lock below are both needed to be held, then - * the cifs_tcp_ses_lock must be grabbed first and released last. - */ -GLOBAL_EXTERN spinlock_t cifs_file_list_lock; - #ifdef CONFIG_CIFS_DNOTIFY_EXPERIMENTAL /* unused temporarily */ /* Outstanding dir notify requests */ GLOBAL_EXTERN struct list_head GlobalDnotifyReqList; -- cgit v1.2.1