pnfs-obj: osd raid engine read/write implementation

With the use of the in-kernel osd library. Implement read/write
of data from/to osd-objects according to information specified
in the objects-layout.

Support for stripping over mirrors with a received stripe_unit.
There are however a few constrains which are not supported:
 1. Stripe Unit must be a multiple of PAGE_SIZE
 2. stripe length (stripe_unit * number_of_stripes) can not be
    bigger then 32bit.

Also support raid-groups and partial-layout. Partial-layout is
when not all the groups are received on the line, addressing
only a partial range of the file.

TODO:
  Only raid0! raid 4/5/6 support will come at later stage

A none supported layout will send IO through the MDS

[Important fallout from the last rebase]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
[gfp_flags]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

fs/nfs/objlayout/objlayout.c

@@ -128,6 +128,260 @@ objlayout_free_lseg(struct pnfs_layout_segment *lseg)
 	objio_free_lseg(lseg);
 }
 
+/*
+ * I/O Operations
+ */
+static inline u64
+end_offset(u64 start, u64 len)
+{
+	u64 end;
+
+	end = start + len;
+	return end >= start ? end : NFS4_MAX_UINT64;
+}
+
+/* last octet in a range */
+static inline u64
+last_byte_offset(u64 start, u64 len)
+{
+	u64 end;
+
+	BUG_ON(!len);
+	end = start + len;
+	return end > start ? end - 1 : NFS4_MAX_UINT64;
+}
+
+static struct objlayout_io_state *
+objlayout_alloc_io_state(struct pnfs_layout_hdr *pnfs_layout_type,
+			struct page **pages,
+			unsigned pgbase,
+			loff_t offset,
+			size_t count,
+			struct pnfs_layout_segment *lseg,
+			void *rpcdata,
+			gfp_t gfp_flags)
+{
+	struct objlayout_io_state *state;
+	u64 lseg_end_offset;
+
+	dprintk("%s: allocating io_state\n", __func__);
+	if (objio_alloc_io_state(lseg, &state, gfp_flags))
+		return NULL;
+
+	BUG_ON(offset < lseg->pls_range.offset);
+	lseg_end_offset = end_offset(lseg->pls_range.offset,
+				     lseg->pls_range.length);
+	BUG_ON(offset >= lseg_end_offset);
+	if (offset + count > lseg_end_offset) {
+		count = lseg->pls_range.length -
+				(offset - lseg->pls_range.offset);
+		dprintk("%s: truncated count %Zd\n", __func__, count);
+	}
+
+	if (pgbase > PAGE_SIZE) {
+		pages += pgbase >> PAGE_SHIFT;
+		pgbase &= ~PAGE_MASK;
+	}
+
+	state->lseg = lseg;
+	state->rpcdata = rpcdata;
+	state->pages = pages;
+	state->pgbase = pgbase;
+	state->nr_pages = (pgbase + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	state->offset = offset;
+	state->count = count;
+	state->sync = 0;
+
+	return state;
+}
+
+static void
+objlayout_free_io_state(struct objlayout_io_state *state)
+{
+	dprintk("%s: freeing io_state\n", __func__);
+	if (unlikely(!state))
+		return;
+
+	objio_free_io_state(state);
+}
+
+/*
+ * I/O done common code
+ */
+static void
+objlayout_iodone(struct objlayout_io_state *state)
+{
+	dprintk("%s: state %p status\n", __func__, state);
+
+	objlayout_free_io_state(state);
+}
+
+/* Function scheduled on rpc workqueue to call ->nfs_readlist_complete().
+ * This is because the osd completion is called with ints-off from
+ * the block layer
+ */
+static void _rpc_read_complete(struct work_struct *work)
+{
+	struct rpc_task *task;
+	struct nfs_read_data *rdata;
+
+	dprintk("%s enter\n", __func__);
+	task = container_of(work, struct rpc_task, u.tk_work);
+	rdata = container_of(task, struct nfs_read_data, task);
+
+	pnfs_ld_read_done(rdata);
+}
+
+void
+objlayout_read_done(struct objlayout_io_state *state, ssize_t status, bool sync)
+{
+	int eof = state->eof;
+	struct nfs_read_data *rdata;
+
+	state->status = status;
+	dprintk("%s: Begin status=%ld eof=%d\n", __func__, status, eof);
+	rdata = state->rpcdata;
+	rdata->task.tk_status = status;
+	if (status >= 0) {
+		rdata->res.count = status;
+		rdata->res.eof = eof;
+	}
+	objlayout_iodone(state);
+	/* must not use state after this point */
+
+	if (sync)
+		pnfs_ld_read_done(rdata);
+	else {
+		INIT_WORK(&rdata->task.u.tk_work, _rpc_read_complete);
+		schedule_work(&rdata->task.u.tk_work);
+	}
+}
+
+/*
+ * Perform sync or async reads.
+ */
+enum pnfs_try_status
+objlayout_read_pagelist(struct nfs_read_data *rdata)
+{
+	loff_t offset = rdata->args.offset;
+	size_t count = rdata->args.count;
+	struct objlayout_io_state *state;
+	ssize_t status = 0;
+	loff_t eof;
+
+	dprintk("%s: Begin inode %p offset %llu count %d\n",
+		__func__, rdata->inode, offset, (int)count);
+
+	eof = i_size_read(rdata->inode);
+	if (unlikely(offset + count > eof)) {
+		if (offset >= eof) {
+			status = 0;
+			rdata->res.count = 0;
+			rdata->res.eof = 1;
+			goto out;
+		}
+		count = eof - offset;
+	}
+
+	state = objlayout_alloc_io_state(NFS_I(rdata->inode)->layout,
+					 rdata->args.pages, rdata->args.pgbase,
+					 offset, count,
+					 rdata->lseg, rdata,
+					 GFP_KERNEL);
+	if (unlikely(!state)) {
+		status = -ENOMEM;
+		goto out;
+	}
+
+	state->eof = state->offset + state->count >= eof;
+
+	status = objio_read_pagelist(state);
+ out:
+	dprintk("%s: Return status %Zd\n", __func__, status);
+	rdata->pnfs_error = status;
+	return PNFS_ATTEMPTED;
+}
+
+/* Function scheduled on rpc workqueue to call ->nfs_writelist_complete().
+ * This is because the osd completion is called with ints-off from
+ * the block layer
+ */
+static void _rpc_write_complete(struct work_struct *work)
+{
+	struct rpc_task *task;
+	struct nfs_write_data *wdata;
+
+	dprintk("%s enter\n", __func__);
+	task = container_of(work, struct rpc_task, u.tk_work);
+	wdata = container_of(task, struct nfs_write_data, task);
+
+	pnfs_ld_write_done(wdata);
+}
+
+void
+objlayout_write_done(struct objlayout_io_state *state, ssize_t status,
+		     bool sync)
+{
+	struct nfs_write_data *wdata;
+
+	dprintk("%s: Begin\n", __func__);
+	wdata = state->rpcdata;
+	state->status = status;
+	wdata->task.tk_status = status;
+	if (status >= 0) {
+		wdata->res.count = status;
+		wdata->verf.committed = state->committed;
+		dprintk("%s: Return status %d committed %d\n",
+			__func__, wdata->task.tk_status,
+			wdata->verf.committed);
+	} else
+		dprintk("%s: Return status %d\n",
+			__func__, wdata->task.tk_status);
+	objlayout_iodone(state);
+	/* must not use state after this point */
+
+	if (sync)
+		pnfs_ld_write_done(wdata);
+	else {
+		INIT_WORK(&wdata->task.u.tk_work, _rpc_write_complete);
+		schedule_work(&wdata->task.u.tk_work);
+	}
+}
+
+/*
+ * Perform sync or async writes.
+ */
+enum pnfs_try_status
+objlayout_write_pagelist(struct nfs_write_data *wdata,
+			 int how)
+{
+	struct objlayout_io_state *state;
+	ssize_t status;
+
+	dprintk("%s: Begin inode %p offset %llu count %u\n",
+		__func__, wdata->inode, wdata->args.offset, wdata->args.count);
+
+	state = objlayout_alloc_io_state(NFS_I(wdata->inode)->layout,
+					 wdata->args.pages,
+					 wdata->args.pgbase,
+					 wdata->args.offset,
+					 wdata->args.count,
+					 wdata->lseg, wdata,
+					 GFP_NOFS);
+	if (unlikely(!state)) {
+		status = -ENOMEM;
+		goto out;
+	}
+
+	state->sync = how & FLUSH_SYNC;
+
+	status = objio_write_pagelist(state, how & FLUSH_STABLE);
+ out:
+	dprintk("%s: Return status %Zd\n", __func__, status);
+	wdata->pnfs_error = status;
+	return PNFS_ATTEMPTED;
+}
+
 /*
  * Get Device Info API for io engines
  */

fs/nfs/objlayout/objlayout.h

@@ -58,6 +58,26 @@ OBJLAYOUT(struct pnfs_layout_hdr *lo)
 	return container_of(lo, struct objlayout, pnfs_layout);
 }
 
+/*
+ * per-I/O operation state
+ * embedded in objects provider io_state data structure
+ */
+struct objlayout_io_state {
+	struct pnfs_layout_segment *lseg;
+
+	struct page **pages;
+	unsigned pgbase;
+	unsigned nr_pages;
+	unsigned long count;
+	loff_t offset;
+	bool sync;
+
+	void *rpcdata;
+	int status;             /* res */
+	int eof;                /* res */
+	int committed;          /* res */
+};
+
 /*
  * Raid engine I/O API
  */
@@ -68,9 +88,24 @@ extern int objio_alloc_lseg(struct pnfs_layout_segment **outp,
 	gfp_t gfp_flags);
 extern void objio_free_lseg(struct pnfs_layout_segment *lseg);
 
+extern int objio_alloc_io_state(
+	struct pnfs_layout_segment *lseg,
+	struct objlayout_io_state **outp,
+	gfp_t gfp_flags);
+extern void objio_free_io_state(struct objlayout_io_state *state);
+
+extern ssize_t objio_read_pagelist(struct objlayout_io_state *ol_state);
+extern ssize_t objio_write_pagelist(struct objlayout_io_state *ol_state,
+				    bool stable);
+
 /*
  * callback API
  */
+extern void objlayout_read_done(struct objlayout_io_state *state,
+				ssize_t status, bool sync);
+extern void objlayout_write_done(struct objlayout_io_state *state,
+				 ssize_t status, bool sync);
+
 extern int objlayout_get_deviceinfo(struct pnfs_layout_hdr *pnfslay,
 	struct nfs4_deviceid *d_id, struct pnfs_osd_deviceaddr **deviceaddr,
 	gfp_t gfp_flags);
@@ -89,4 +124,11 @@ extern struct pnfs_layout_segment *objlayout_alloc_lseg(
 	gfp_t gfp_flags);
 extern void objlayout_free_lseg(struct pnfs_layout_segment *);
 
+extern enum pnfs_try_status objlayout_read_pagelist(
+	struct nfs_read_data *);
+
+extern enum pnfs_try_status objlayout_write_pagelist(
+	struct nfs_write_data *,
+	int how);
+
 #endif /* _OBJLAYOUT_H */