On 2010-09-10 22:23, Trond Myklebust wrote: > On Thu, 2010-09-02 at 14:00 -0400, Fred Isaman wrote: >> From: The pNFS Team <linux-nfs@xxxxxxxxxxxxxxx> >> >> Allow a module implementing a layout type to register, and >> have its mount/umount routines called for filesystems that >> the server declares support it. >> >> Signed-off-by: TBD - melding/reorganization of several patches >> --- >> Documentation/filesystems/nfs/00-INDEX | 2 + >> Documentation/filesystems/nfs/pnfs.txt | 48 +++++++++++++++++++ >> fs/nfs/Kconfig | 2 +- >> fs/nfs/pnfs.c | 79 +++++++++++++++++++++++++++++++- >> fs/nfs/pnfs.h | 14 ++++++ >> 5 files changed, 142 insertions(+), 3 deletions(-) >> create mode 100644 Documentation/filesystems/nfs/pnfs.txt >> >> diff --git a/Documentation/filesystems/nfs/00-INDEX b/Documentation/filesystems/nfs/00-INDEX >> index 2f68cd6..8d930b9 100644 >> --- a/Documentation/filesystems/nfs/00-INDEX >> +++ b/Documentation/filesystems/nfs/00-INDEX >> @@ -12,5 +12,7 @@ nfs-rdma.txt >> - how to install and setup the Linux NFS/RDMA client and server software >> nfsroot.txt >> - short guide on setting up a diskless box with NFS root filesystem. >> +pnfs.txt >> + - short explanation of some of the internals of the pnfs code >> rpc-cache.txt >> - introduction to the caching mechanisms in the sunrpc layer. >> diff --git a/Documentation/filesystems/nfs/pnfs.txt b/Documentation/filesystems/nfs/pnfs.txt >> new file mode 100644 >> index 0000000..bc0b9cf >> --- /dev/null >> +++ b/Documentation/filesystems/nfs/pnfs.txt >> @@ -0,0 +1,48 @@ >> +Reference counting in pnfs: >> +========================== >> + >> +The are several inter-related caches. We have layouts which can >> +reference multiple devices, each of which can reference multiple data servers. >> +Each data server can be referenced by multiple devices. Each device >> +can be referenced by multiple layouts. To keep all of this straight, >> +we need to reference count. >> + >> + >> +struct pnfs_layout_hdr >> +---------------------- >> +The on-the-wire command LAYOUTGET corresponds to struct >> +pnfs_layout_segment, usually referred to by the variable name lseg. >> +Each nfs_inode may hold a pointer to a cache of of these layout >> +segments in nfsi->layout, of type struct pnfs_layout_hdr. >> + >> +We reference the header for the inode pointing to it, across each >> +outstanding RPC call that references it (LAYOUTGET, LAYOUTRETURN, >> +LAYOUTCOMMIT), and for each lseg held within. >> + >> +Each header is also (when non-empty) put on a list associated with >> +struct nfs_client (cl_layouts). Being put on this list does not bump >> +the reference count, as the layout is kept around by the lseg that >> +keeps it in the list. >> + >> +deviceid_cache >> +-------------- >> +lsegs reference device ids, which are resolved per nfs_client and >> +layout driver type. The device ids are held in a RCU cache (struct >> +nfs4_deviceid_cache). The cache itself is referenced across each >> +mount. The entries (struct nfs4_deviceid) themselves are held across >> +the lifetime of each lseg referencing them. >> + >> +RCU is used because the deviceid is basically a write once, read many >> +data structure. The hlist size of 32 buckets needs better >> +justification, but seems reasonable given that we can have multiple >> +deviceid's per filesystem, and multiple filesystems per nfs_client. >> + >> +The hash code is copied from the nfsd code base. A discussion of >> +hashing and variations of this algorithm can be found at: >> +http://groups.google.com/group/comp.lang.c/browse_thread/thread/9522965e2b8d3809 >> + >> +data server cache >> +----------------- >> +file driver devices refer to data servers, which are kept in a module >> +level cache. Its reference is held over the lifetime of the deviceid >> +pointing to it. >> diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig >> index 6c2aad4..5f1b936 100644 >> --- a/fs/nfs/Kconfig >> +++ b/fs/nfs/Kconfig >> @@ -78,7 +78,7 @@ config NFS_V4_1 >> depends on NFS_V4 && EXPERIMENTAL >> help >> This option enables support for minor version 1 of the NFSv4 protocol >> - (draft-ietf-nfsv4-minorversion1) in the kernel's NFS client. >> + (RFC 5661) in the kernel's NFS client. >> >> If unsure, say N. >> >> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c >> index 2e5dba1..8d503fc 100644 >> --- a/fs/nfs/pnfs.c >> +++ b/fs/nfs/pnfs.c >> @@ -32,16 +32,48 @@ >> >> #define NFSDBG_FACILITY NFSDBG_PNFS >> >> -/* STUB that returns the equivalent of "no module found" */ >> +/* Locking: >> + * >> + * pnfs_spinlock: >> + * protects pnfs_modules_tbl. >> + */ >> +static DEFINE_SPINLOCK(pnfs_spinlock); >> + >> +/* >> + * pnfs_modules_tbl holds all pnfs modules >> + */ >> +static LIST_HEAD(pnfs_modules_tbl); >> + >> +/* Return the registered pnfs layout driver module matching given id */ >> +static struct pnfs_layoutdriver_type * >> +find_pnfs_driver_locked(u32 id) { >> + struct pnfs_layoutdriver_type *local; >> + >> + dprintk("PNFS: %s: Searching for %u\n", __func__, id); >> + list_for_each_entry(local, &pnfs_modules_tbl, pnfs_tblid) >> + if (local->id == id) >> + goto out; >> + local = NULL; >> +out: >> + return local; >> +} >> + >> static struct pnfs_layoutdriver_type * >> find_pnfs_driver(u32 id) { >> - return NULL; >> + struct pnfs_layoutdriver_type *local; >> + >> + spin_lock(&pnfs_spinlock); >> + local = find_pnfs_driver_locked(id); > > Don't you want some kind of reference count on this? I'd assume that you > probably need a module_get() with a corresponding module_put() when you > are done using the layoutdriver. > >> + spin_unlock(&pnfs_spinlock); >> + return local; >> } >> >> /* Unitialize a mountpoint in a layout driver */ >> void >> unset_pnfs_layoutdriver(struct nfs_server *nfss) >> { >> + if (nfss->pnfs_curr_ld) >> + nfss->pnfs_curr_ld->ld_io_ops->uninitialize_mountpoint(nfss->nfs_client); > > That 'uninitialize_mountpoint' name doesn't make any sense. The > nfs_client parameter isn't associated to a particular mountpoint. > We call these methods upon creating and destroying the nfs_server, respectively. Later on, in the post-submit world, we change this parameter to a struct nfs_server * for the blocks layout driver. The motivation is to issue GETDEVICELIST at mount time. For the file layout at its present state we only use the nfs_client for the deviceid cache. Note that to support multiple layout types per server (possibly for different filesystems exported by that server we'll need per-layouttype deviceid cache on the nfs_client. We can have different methods for the per-nfs_client event and the per-nfs_server event and call them correspondingly. Benny >> nfss->pnfs_curr_ld = NULL; >> } >> >> @@ -68,6 +100,12 @@ set_pnfs_layoutdriver(struct nfs_server *server, u32 id) >> goto out_no_driver; >> } >> } >> + if (ld_type->ld_io_ops->initialize_mountpoint(server->nfs_client)) { > > Ditto. > >> + printk(KERN_ERR >> + "%s: Error initializing mount point for layout driver %u.\n", >> + __func__, id); >> + goto out_no_driver; >> + } >> server->pnfs_curr_ld = ld_type; >> dprintk("%s: pNFS module for %u set\n", __func__, id); >> return; >> @@ -76,3 +114,40 @@ out_no_driver: >> dprintk("%s: Using NFSv4 I/O\n", __func__); >> server->pnfs_curr_ld = NULL; >> } >> + >> +int >> +pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *ld_type) >> +{ >> + struct layoutdriver_io_operations *io_ops = ld_type->ld_io_ops; >> + int status = -EINVAL; >> + >> + if (!io_ops) { >> + printk(KERN_ERR "%s Layout driver must provide io_ops\n", >> + __func__); >> + return status; >> + } >> + >> + spin_lock(&pnfs_spinlock); >> + if (!find_pnfs_driver_locked(ld_type->id)) { >> + list_add(&ld_type->pnfs_tblid, &pnfs_modules_tbl); >> + status = 0; >> + dprintk("%s Registering id:%u name:%s\n", __func__, ld_type->id, >> + ld_type->name); >> + } else >> + printk(KERN_ERR "%s Module with id %d already loaded!\n", >> + __func__, ld_type->id); >> + spin_unlock(&pnfs_spinlock); >> + >> + return status; >> +} >> +EXPORT_SYMBOL(pnfs_register_layoutdriver); >> + >> +void >> +pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type) >> +{ >> + dprintk("%s Deregistering id:%u\n", __func__, ld_type->id); >> + spin_lock(&pnfs_spinlock); >> + list_del(&ld_type->pnfs_tblid); >> + spin_unlock(&pnfs_spinlock); >> +} >> +EXPORT_SYMBOL(pnfs_unregister_layoutdriver); >> diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h >> index 3281fbf..9049b9a 100644 >> --- a/fs/nfs/pnfs.h >> +++ b/fs/nfs/pnfs.h >> @@ -16,8 +16,22 @@ >> >> /* Per-layout driver specific registration structure */ >> struct pnfs_layoutdriver_type { >> + struct list_head pnfs_tblid; >> + const u32 id; >> + const char *name; >> + struct layoutdriver_io_operations *ld_io_ops; >> }; >> >> +/* Layout driver I/O operations. */ >> +struct layoutdriver_io_operations { >> + /* Registration information for a new mounted file system */ >> + int (*initialize_mountpoint) (struct nfs_client *); >> + int (*uninitialize_mountpoint) (struct nfs_client *); >> +}; >> + >> +extern int pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *); >> +extern void pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *); >> + >> void set_pnfs_layoutdriver(struct nfs_server *, u32 id); >> void unset_pnfs_layoutdriver(struct nfs_server *); >> > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
