Re: [PATCH 09/13] RFC: nfs: create and destroy inode's layout cache

Trond Myklebust
2010-09-10T19:43:55Z

On Thu, 2010-09-02 at 14:00 -0400, Fred Isaman wrote:
> From: The pNFS Team <linux-nfs@vger.kernel.org>
>
> At the start of the io paths, try to grab the relevant layout
> information. This will initiate the inode's layout cache, but
> stubs ensure the cache stays empty.
>
> Signed-off-by: TBD - melding/reorganization of several patches
> ---
> fs/nfs/file.c | 5 ++
> fs/nfs/inode.c | 3 +
> fs/nfs/pnfs.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++
> fs/nfs/pnfs.h | 39 +++++++++++++
> fs/nfs/read.c | 3 +
> include/linux/nfs_fs.h | 3 +
> 6 files changed, 193 insertions(+), 0 deletions(-)
>
> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
> index eb51bd6..10ebdfb 100644
> --- a/fs/nfs/file.c
> +++ b/fs/nfs/file.c
> @@ -36,6 +36,7 @@
> #include "internal.h"
> #include "iostat.h"
> #include "fscache.h"
> +#include "pnfs.h"
>
> #define NFSDBG_FACILITY NFSDBG_FILE
>
> @@ -386,6 +387,10 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
> file->f_path.dentry->d_name.name,
> mapping->host->i_ino, len, (long long) pos);
>
> + pnfs_update_layout(mapping->host,
> + nfs_file_open_context(file),
> + IOMODE_RW);
> +
> start:
> /*
> * Prevent starvation issues if someone is doing a consistency
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 7d2d6c7..0dc6dad 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -48,6 +48,7 @@
> #include "internal.h"
> #include "fscache.h"
> #include "dns_resolve.h"
> +#include "pnfs.h"
>
> #define NFSDBG_FACILITY NFSDBG_VFS
>
> @@ -1409,6 +1410,7 @@ void nfs4_evict_inode(struct inode *inode)
> {
> truncate_inode_pages(&inode->i_data, 0);
> end_writeback(inode);
> + pnfs_destroy_layout(NFS_I(inode));
> /* If we are holding a delegation, return it! */
> nfs_inode_return_delegation_noreclaim(inode);
> /* First call standard NFS clear_inode() code */
> @@ -1446,6 +1448,7 @@ static inline void nfs4_init_once(struct nfs_inode *nfsi)
> nfsi->delegation = NULL;
> nfsi->delegation_state = 0;
> init_rwsem(&nfsi->rwsem);
> + nfsi->layout = NULL;
> #endif
> }
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index 8d503fc..65f923b 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -151,3 +151,143 @@ pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
> spin_unlock(&pnfs_spinlock);
> }
> EXPORT_SYMBOL(pnfs_unregister_layoutdriver);
> +
> +static void
> +get_layout_hdr_locked(struct pnfs_layout_hdr *lo)
> +{
> + assert_spin_locked(&lo->inode->i_lock);
> + lo->refcount++;
> +}
> +
> +static void
> +put_layout_hdr_locked(struct pnfs_layout_hdr *lo)
> +{
> + assert_spin_locked(&lo->inode->i_lock);
> + BUG_ON(lo->refcount <= 0);
> +
> + lo->refcount--;
> + if (!lo->refcount) {
> + dprintk("%s: freeing layout cache %p\n", __func__, lo);
> + NFS_I(lo->inode)->layout = NULL;
> + kfree(lo);
> + }
> +}
> +
> +void
> +pnfs_destroy_layout(struct nfs_inode *nfsi)
> +{
> + struct pnfs_layout_hdr *lo;
> +
> + spin_lock(&nfsi->vfs_inode.i_lock);
> + lo = nfsi->layout;
> + if (lo) {
> + /* Matched by refcount set to 1 in alloc_init_layout_hdr */
> + put_layout_hdr_locked(lo);
> + }
> + spin_unlock(&nfsi->vfs_inode.i_lock);
> +}
> +
> +/* STUB - pretend LAYOUTGET to server failed */
> +static struct pnfs_layout_segment *
> +send_layoutget(struct pnfs_layout_hdr *lo,
> + struct nfs_open_context *ctx,
> + u32 iomode)
> +{
> + struct inode *ino = lo->inode;
> +
> + set_bit(lo_fail_bit(iomode), &lo->state);
> + spin_lock(&ino->i_lock);
> + put_layout_hdr_locked(lo);
> + spin_unlock(&ino->i_lock);
> + return NULL;
> +}
> +
> +static struct pnfs_layout_hdr *
> +alloc_init_layout_hdr(struct inode *ino)
> +{
> + struct pnfs_layout_hdr *lo;
> +
> + lo = kzalloc(sizeof(struct pnfs_layout_hdr), GFP_KERNEL);
> + if (!lo)
> + return NULL;
> + lo->refcount = 1;
> + lo->inode = ino;
> + return lo;
> +}
> +
> +static struct pnfs_layout_hdr *
> +pnfs_find_alloc_layout(struct inode *ino)
> +{
> + struct nfs_inode *nfsi = NFS_I(ino);
> + struct pnfs_layout_hdr *new = NULL;
> +
> + dprintk("%s Begin ino=%p layout=%p\n", __func__, ino, nfsi->layout);
> +
> + assert_spin_locked(&ino->i_lock);
> + if (nfsi->layout)
> + return nfsi->layout;
> +
> + spin_unlock(&ino->i_lock);
> + new = alloc_init_layout_hdr(ino);
> + spin_lock(&ino->i_lock);
> +
> + if (likely(nfsi->layout == NULL)) /* Won the race? */
> + nfsi->layout = new;
> + else
> + kfree(new);
> + return nfsi->layout;
> +}
> +
> +/* STUB - LAYOUTGET never succeeds, so cache is empty */
> +static struct pnfs_layout_segment *
> +pnfs_has_layout(struct pnfs_layout_hdr *lo, u32 iomode)
> +{
> + return NULL;
> +}
> +
> +/*
> + * Layout segment is retreived from the server if not cached.
> + * The appropriate layout segment is referenced and returned to the caller.
> + */
> +struct pnfs_layout_segment *
> +pnfs_update_layout(struct inode *ino,
> + struct nfs_open_context *ctx,
> + enum pnfs_iomode iomode)
> +{
> + struct nfs_inode *nfsi = NFS_I(ino);
> + struct pnfs_layout_hdr *lo;
> + struct pnfs_layout_segment *lseg = NULL;
> +
> + if (!pnfs_enabled_sb(NFS_SERVER(ino)))
> + return NULL;
> + spin_lock(&ino->i_lock);
> + lo = pnfs_find_alloc_layout(ino);
> + if (lo == NULL) {
> + dprintk("%s ERROR: can't get pnfs_layout_hdr\n", __func__);
> + goto out_unlock;
> + }
> +
> + /* Check to see if the layout for the given range already exists */
> + lseg = pnfs_has_layout(lo, iomode);
> + if (lseg) {
> + dprintk("%s: Using cached lseg %p for iomode %d)\n",
> + __func__, lseg, iomode);
> + goto out_unlock;
> + }
> +
> + /* if LAYOUTGET already failed once we don't try again */
> + if (test_bit(lo_fail_bit(iomode), &nfsi->layout->state))
> + goto out_unlock;
> +
> + get_layout_hdr_locked(lo);
> + spin_unlock(&ino->i_lock);
> +
> + lseg = send_layoutget(lo, ctx, iomode);
> +out:
> + dprintk("%s end, state 0x%lx lseg %p\n", __func__,
> + nfsi->layout->state, lseg);
> + return lseg;
> +out_unlock:
> + spin_unlock(&ino->i_lock);
> + goto out;
> +}
> diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
> index 9049b9a..b63b445 100644
> --- a/fs/nfs/pnfs.h
> +++ b/fs/nfs/pnfs.h
> @@ -14,6 +14,11 @@
>
> #define LAYOUT_NFSV4_1_MODULE_PREFIX "nfs-layouttype4"
>
> +enum {
> + NFS_LAYOUT_RO_FAILED = 0, /* get ro layout failed stop trying */
> + NFS_LAYOUT_RW_FAILED, /* get rw layout failed stop trying */
> +};
> +
> /* Per-layout driver specific registration structure */
> struct pnfs_layoutdriver_type {
> struct list_head pnfs_tblid;
> @@ -22,6 +27,12 @@ struct pnfs_layoutdriver_type {
> struct layoutdriver_io_operations *ld_io_ops;
> };
>
> +struct pnfs_layout_hdr {
> + int refcount;
^^^^^ Why not make this 'unsigned int', and/or 'unsigned long'?
> + unsigned long state;
> + struct inode *inode;
> +};
> +
> /* Layout driver I/O operations. */
> struct layoutdriver_io_operations {
> /* Registration information for a new mounted file system */
> @@ -32,11 +43,39 @@ struct layoutdriver_io_operations {
> extern int pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *);
> extern void pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *);
>
> +struct pnfs_layout_segment *
> +pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
> + enum pnfs_iomode access_type);
> void set_pnfs_layoutdriver(struct nfs_server *, u32 id);
> void unset_pnfs_layoutdriver(struct nfs_server *);
> +void pnfs_destroy_layout(struct nfs_inode *);
> +
> +
> +static inline int lo_fail_bit(u32 iomode)
> +{
> + return iomode == IOMODE_RW ?
> + NFS_LAYOUT_RW_FAILED : NFS_LAYOUT_RO_FAILED;
> +}
> +
> +/* Return true if a layout driver is being used for this mountpoint */
> +static inline int pnfs_enabled_sb(struct nfs_server *nfss)
> +{
> + return nfss->pnfs_curr_ld != NULL;
> +}
>
> #else /* CONFIG_NFS_V4_1 */
>
> +static inline void pnfs_destroy_layout(struct nfs_inode *nfsi)
> +{
> +}
> +
> +static inline struct pnfs_layout_segment *
> +pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
> + enum pnfs_iomode access_type)
> +{
> + return NULL;
> +}
> +
> static inline void set_pnfs_layoutdriver(struct nfs_server *s, u32 id)
> {
> }
> diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> index 87adc27..f7eb66f 100644
> --- a/fs/nfs/read.c
> +++ b/fs/nfs/read.c
> @@ -25,6 +25,7 @@
> #include "internal.h"
> #include "iostat.h"
> #include "fscache.h"
> +#include "pnfs.h"
>
> #define NFSDBG_FACILITY NFSDBG_PAGECACHE
>
> @@ -121,6 +122,7 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
> len = nfs_page_length(page);
> if (len == 0)
> return nfs_return_empty_page(page);
> + pnfs_update_layout(inode, ctx, IOMODE_READ);
> new = nfs_create_request(ctx, inode, page, 0, len);
> if (IS_ERR(new)) {
> unlock_page(page);
> @@ -625,6 +627,7 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
> if (ret == 0)
> goto read_complete; /* all pages were read */
>
> + pnfs_update_layout(inode, desc.ctx, IOMODE_READ);
> if (rsize < PAGE_CACHE_SIZE)
> nfs_pageio_init(&pgio, inode, nfs_pagein_multi, rsize, 0);
> else
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index a0f49a3..ebd87a9 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -188,6 +188,9 @@ struct nfs_inode {
> struct nfs_delegation *delegation;
> fmode_t delegation_state;
> struct rw_semaphore rwsem;
> +
> + /* pNFS layout information */
> + struct pnfs_layout_hdr *layout;
> #endif /* CONFIG_NFS_V4*/
> #ifdef CONFIG_NFS_FSCACHE
> struct fscache_cookie *fscache;