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authorSteve French <smfrench@gmail.com>2016-09-22 18:58:16 -0500
committerSteve French <smfrench@gmail.com>2016-10-12 12:08:32 -0500
commit3afca265b5f53a0b15b79531c13858049505582d (patch)
treeac9c7c97ee38fb4c156731643120833c5e53f63c /fs/cifs/cifsglob.h
parentd171356ff11ab1825e456dfb979755e01b3c54a1 (diff)
downloadlinux-3afca265b5f53a0b15b79531c13858049505582d.tar.bz2
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 <stable@vger.kernel.org> Signed-off-by: Steve French <steve.french@primarydata.com> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Reviewed-by: Germano Percossi <germano.percossi@citrix.com>
Diffstat (limited to 'fs/cifs/cifsglob.h')
-rw-r--r--fs/cifs/cifsglob.h30
1 files changed, 15 insertions, 15 deletions
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;