Commit beaec07b authored by Boaz Harrosh's avatar Boaz Harrosh
Browse files

exofs: address_space_operations 



OK Now we start to read and write from osd-objects. We try to
collect at most contiguous pages as possible in a single write/read.
The first page index is the object's offset.

TODO:
   In 64-bit a single bio can carry at most 128 pages.
   Add support of chaining multiple bios

Signed-off-by: default avatarBoaz Harrosh <bharrosh@panasas.com>
parent 982980d7

fs/exofs/exofs.h

+6 −0
Original line number Diff line number Diff line
@@ -130,6 +130,9 @@ static inline struct exofs_i_info *exofs_i(struct inode *inode) 
/* inode.c               */

void exofs_truncate(struct inode *inode);

int exofs_setattr(struct dentry *, struct iattr *);

int exofs_write_begin(struct file *file, struct address_space *mapping,

		loff_t pos, unsigned len, unsigned flags,

		struct page **pagep, void **fsdata);



/*********************

 * operation vectors *
@@ -138,6 +141,9 @@ int exofs_setattr(struct dentry *, struct iattr *); 
extern const struct inode_operations exofs_file_inode_operations;

extern const struct file_operations exofs_file_operations;



/* inode.c           */

extern const struct address_space_operations exofs_aops;



/* symlink.c         */

extern const struct inode_operations exofs_symlink_inode_operations;

extern const struct inode_operations exofs_fast_symlink_inode_operations;

fs/exofs/inode.c

+697 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 


#include <linux/writeback.h>

#include <linux/buffer_head.h>

#include <scsi/scsi_device.h>



#include "exofs.h"
@@ -42,6 +43,702 @@ 
#  define EXOFS_DEBUG_OBJ_ISIZE 1

#endif



struct page_collect {

	struct exofs_sb_info *sbi;

	struct request_queue *req_q;

	struct inode *inode;

	unsigned expected_pages;



	struct bio *bio;

	unsigned nr_pages;

	unsigned long length;

	loff_t pg_first; /* keep 64bit also in 32-arches */

};



static void _pcol_init(struct page_collect *pcol, unsigned expected_pages,

		struct inode *inode)

{

	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;

	struct request_queue *req_q = sbi->s_dev->scsi_device->request_queue;



	pcol->sbi = sbi;

	pcol->req_q = req_q;

	pcol->inode = inode;

	pcol->expected_pages = expected_pages;



	pcol->bio = NULL;

	pcol->nr_pages = 0;

	pcol->length = 0;

	pcol->pg_first = -1;



	EXOFS_DBGMSG("_pcol_init ino=0x%lx expected_pages=%u\n", inode->i_ino,

		     expected_pages);

}



static void _pcol_reset(struct page_collect *pcol)

{

	pcol->expected_pages -= min(pcol->nr_pages, pcol->expected_pages);



	pcol->bio = NULL;

	pcol->nr_pages = 0;

	pcol->length = 0;

	pcol->pg_first = -1;

	EXOFS_DBGMSG("_pcol_reset ino=0x%lx expected_pages=%u\n",

		     pcol->inode->i_ino, pcol->expected_pages);



	/* this is probably the end of the loop but in writes

	 * it might not end here. don't be left with nothing

	 */

	if (!pcol->expected_pages)

		pcol->expected_pages = 128;

}



static int pcol_try_alloc(struct page_collect *pcol)

{

	int pages = min_t(unsigned, pcol->expected_pages, BIO_MAX_PAGES);



	for (; pages; pages >>= 1) {

		pcol->bio = bio_alloc(GFP_KERNEL, pages);

		if (likely(pcol->bio))

			return 0;

	}



	EXOFS_ERR("Failed to kcalloc expected_pages=%u\n",

		  pcol->expected_pages);

	return -ENOMEM;

}



static void pcol_free(struct page_collect *pcol)

{

	bio_put(pcol->bio);

	pcol->bio = NULL;

}



static int pcol_add_page(struct page_collect *pcol, struct page *page,

			 unsigned len)

{

	int added_len = bio_add_pc_page(pcol->req_q, pcol->bio, page, len, 0);

	if (unlikely(len != added_len))

		return -ENOMEM;



	++pcol->nr_pages;

	pcol->length += len;

	return 0;

}



static int update_read_page(struct page *page, int ret)

{

	if (ret == 0) {

		/* Everything is OK */

		SetPageUptodate(page);

		if (PageError(page))

			ClearPageError(page);

	} else if (ret == -EFAULT) {

		/* In this case we were trying to read something that wasn't on

		 * disk yet - return a page full of zeroes.  This should be OK,

		 * because the object should be empty (if there was a write

		 * before this read, the read would be waiting with the page

		 * locked */

		clear_highpage(page);



		SetPageUptodate(page);

		if (PageError(page))

			ClearPageError(page);

		ret = 0; /* recovered error */

		EXOFS_DBGMSG("recovered read error\n");

	} else /* Error */

		SetPageError(page);



	return ret;

}



static void update_write_page(struct page *page, int ret)

{

	if (ret) {

		mapping_set_error(page->mapping, ret);

		SetPageError(page);

	}

	end_page_writeback(page);

}



/* Called at the end of reads, to optionally unlock pages and update their

 * status.

 */

static int __readpages_done(struct osd_request *or, struct page_collect *pcol,

			    bool do_unlock)

{

	struct bio_vec *bvec;

	int i;

	u64 resid;

	u64 good_bytes;

	u64 length = 0;

	int ret = exofs_check_ok_resid(or, &resid, NULL);



	osd_end_request(or);



	if (likely(!ret))

		good_bytes = pcol->length;

	else if (!resid)

		good_bytes = 0;

	else

		good_bytes = pcol->length - resid;



	EXOFS_DBGMSG("readpages_done(0x%lx) good_bytes=0x%llx"

		     " length=0x%lx nr_pages=%u\n",

		     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,

		     pcol->nr_pages);



	__bio_for_each_segment(bvec, pcol->bio, i, 0) {

		struct page *page = bvec->bv_page;

		struct inode *inode = page->mapping->host;

		int page_stat;



		if (inode != pcol->inode)

			continue; /* osd might add more pages at end */



		if (likely(length < good_bytes))

			page_stat = 0;

		else

			page_stat = ret;



		EXOFS_DBGMSG("    readpages_done(0x%lx, 0x%lx) %s\n",

			  inode->i_ino, page->index,

			  page_stat ? "bad_bytes" : "good_bytes");



		ret = update_read_page(page, page_stat);

		if (do_unlock)

			unlock_page(page);

		length += bvec->bv_len;

	}



	pcol_free(pcol);

	EXOFS_DBGMSG("readpages_done END\n");

	return ret;

}



/* callback of async reads */

static void readpages_done(struct osd_request *or, void *p)

{

	struct page_collect *pcol = p;



	__readpages_done(or, pcol, true);

	atomic_dec(&pcol->sbi->s_curr_pending);

	kfree(p);

}



static void _unlock_pcol_pages(struct page_collect *pcol, int ret, int rw)

{

	struct bio_vec *bvec;

	int i;



	__bio_for_each_segment(bvec, pcol->bio, i, 0) {

		struct page *page = bvec->bv_page;



		if (rw == READ)

			update_read_page(page, ret);

		else

			update_write_page(page, ret);



		unlock_page(page);

	}

	pcol_free(pcol);

}



static int read_exec(struct page_collect *pcol, bool is_sync)

{

	struct exofs_i_info *oi = exofs_i(pcol->inode);

	struct osd_obj_id obj = {pcol->sbi->s_pid,

					pcol->inode->i_ino + EXOFS_OBJ_OFF};

	struct osd_request *or = NULL;

	struct page_collect *pcol_copy = NULL;

	loff_t i_start = pcol->pg_first << PAGE_CACHE_SHIFT;

	int ret;



	if (!pcol->bio)

		return 0;



	/* see comment in _readpage() about sync reads */

	WARN_ON(is_sync && (pcol->nr_pages != 1));



	or = osd_start_request(pcol->sbi->s_dev, GFP_KERNEL);

	if (unlikely(!or)) {

		ret = -ENOMEM;

		goto err;

	}



	osd_req_read(or, &obj, pcol->bio, i_start);



	if (is_sync) {

		exofs_sync_op(or, pcol->sbi->s_timeout, oi->i_cred);

		return __readpages_done(or, pcol, false);

	}



	pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);

	if (!pcol_copy) {

		ret = -ENOMEM;

		goto err;

	}



	*pcol_copy = *pcol;

	ret = exofs_async_op(or, readpages_done, pcol_copy, oi->i_cred);

	if (unlikely(ret))

		goto err;



	atomic_inc(&pcol->sbi->s_curr_pending);



	EXOFS_DBGMSG("read_exec obj=0x%llx start=0x%llx length=0x%lx\n",

		  obj.id, _LLU(i_start), pcol->length);



	/* pages ownership was passed to pcol_copy */

	_pcol_reset(pcol);

	return 0;



err:

	if (!is_sync)

		_unlock_pcol_pages(pcol, ret, READ);

	kfree(pcol_copy);

	if (or)

		osd_end_request(or);

	return ret;

}



/* readpage_strip is called either directly from readpage() or by the VFS from

 * within read_cache_pages(), to add one more page to be read. It will try to

 * collect as many contiguous pages as posible. If a discontinuity is

 * encountered, or it runs out of resources, it will submit the previous segment

 * and will start a new collection. Eventually caller must submit the last

 * segment if present.

 */

static int readpage_strip(void *data, struct page *page)

{

	struct page_collect *pcol = data;

	struct inode *inode = pcol->inode;

	struct exofs_i_info *oi = exofs_i(inode);

	loff_t i_size = i_size_read(inode);

	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;

	size_t len;

	int ret;



	/* FIXME: Just for debugging, will be removed */

	if (PageUptodate(page))

		EXOFS_ERR("PageUptodate(0x%lx, 0x%lx)\n", pcol->inode->i_ino,

			  page->index);



	if (page->index < end_index)

		len = PAGE_CACHE_SIZE;

	else if (page->index == end_index)

		len = i_size & ~PAGE_CACHE_MASK;

	else

		len = 0;



	if (!len || !obj_created(oi)) {

		/* this will be out of bounds, or doesn't exist yet.

		 * Current page is cleared and the request is split

		 */

		clear_highpage(page);



		SetPageUptodate(page);

		if (PageError(page))

			ClearPageError(page);



		unlock_page(page);

		EXOFS_DBGMSG("readpage_strip(0x%lx, 0x%lx) empty page,"

			     " splitting\n", inode->i_ino, page->index);



		return read_exec(pcol, false);

	}



try_again:



	if (unlikely(pcol->pg_first == -1)) {

		pcol->pg_first = page->index;

	} else if (unlikely((pcol->pg_first + pcol->nr_pages) !=

		   page->index)) {

		/* Discontinuity detected, split the request */

		ret = read_exec(pcol, false);

		if (unlikely(ret))

			goto fail;

		goto try_again;

	}



	if (!pcol->bio) {

		ret = pcol_try_alloc(pcol);

		if (unlikely(ret))

			goto fail;

	}



	if (len != PAGE_CACHE_SIZE)

		zero_user(page, len, PAGE_CACHE_SIZE - len);



	EXOFS_DBGMSG("    readpage_strip(0x%lx, 0x%lx) len=0x%zx\n",

		     inode->i_ino, page->index, len);



	ret = pcol_add_page(pcol, page, len);

	if (ret) {

		EXOFS_DBGMSG("Failed pcol_add_page pages[i]=%p "

			  "this_len=0x%zx nr_pages=%u length=0x%lx\n",

			  page, len, pcol->nr_pages, pcol->length);



		/* split the request, and start again with current page */

		ret = read_exec(pcol, false);

		if (unlikely(ret))

			goto fail;



		goto try_again;

	}



	return 0;



fail:

	/* SetPageError(page); ??? */

	unlock_page(page);

	return ret;

}



static int exofs_readpages(struct file *file, struct address_space *mapping,

			   struct list_head *pages, unsigned nr_pages)

{

	struct page_collect pcol;

	int ret;



	_pcol_init(&pcol, nr_pages, mapping->host);



	ret = read_cache_pages(mapping, pages, readpage_strip, &pcol);

	if (ret) {

		EXOFS_ERR("read_cache_pages => %d\n", ret);

		return ret;

	}



	return read_exec(&pcol, false);

}



static int _readpage(struct page *page, bool is_sync)

{

	struct page_collect pcol;

	int ret;



	_pcol_init(&pcol, 1, page->mapping->host);



	/* readpage_strip might call read_exec(,async) inside at several places

	 * but this is safe for is_async=0 since read_exec will not do anything

	 * when we have a single page.

	 */

	ret = readpage_strip(&pcol, page);

	if (ret) {

		EXOFS_ERR("_readpage => %d\n", ret);

		return ret;

	}



	return read_exec(&pcol, is_sync);

}



/*

 * We don't need the file

 */

static int exofs_readpage(struct file *file, struct page *page)

{

	return _readpage(page, false);

}



/* Callback for osd_write. All writes are asynchronouse */

static void writepages_done(struct osd_request *or, void *p)

{

	struct page_collect *pcol = p;

	struct bio_vec *bvec;

	int i;

	u64 resid;

	u64  good_bytes;

	u64  length = 0;



	int ret = exofs_check_ok_resid(or, NULL, &resid);



	osd_end_request(or);

	atomic_dec(&pcol->sbi->s_curr_pending);



	if (likely(!ret))

		good_bytes = pcol->length;

	else if (!resid)

		good_bytes = 0;

	else

		good_bytes = pcol->length - resid;



	EXOFS_DBGMSG("writepages_done(0x%lx) good_bytes=0x%llx"

		     " length=0x%lx nr_pages=%u\n",

		     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,

		     pcol->nr_pages);



	__bio_for_each_segment(bvec, pcol->bio, i, 0) {

		struct page *page = bvec->bv_page;

		struct inode *inode = page->mapping->host;

		int page_stat;



		if (inode != pcol->inode)

			continue; /* osd might add more pages to a bio */



		if (likely(length < good_bytes))

			page_stat = 0;

		else

			page_stat = ret;



		update_write_page(page, page_stat);

		unlock_page(page);

		EXOFS_DBGMSG("    writepages_done(0x%lx, 0x%lx) status=%d\n",

			     inode->i_ino, page->index, page_stat);



		length += bvec->bv_len;

	}



	pcol_free(pcol);

	kfree(pcol);

	EXOFS_DBGMSG("writepages_done END\n");

}



static int write_exec(struct page_collect *pcol)

{

	struct exofs_i_info *oi = exofs_i(pcol->inode);

	struct osd_obj_id obj = {pcol->sbi->s_pid,

					pcol->inode->i_ino + EXOFS_OBJ_OFF};

	struct osd_request *or = NULL;

	struct page_collect *pcol_copy = NULL;

	loff_t i_start = pcol->pg_first << PAGE_CACHE_SHIFT;

	int ret;



	if (!pcol->bio)

		return 0;



	or = osd_start_request(pcol->sbi->s_dev, GFP_KERNEL);

	if (unlikely(!or)) {

		EXOFS_ERR("write_exec: Faild to osd_start_request()\n");

		ret = -ENOMEM;

		goto err;

	}



	pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);

	if (!pcol_copy) {

		EXOFS_ERR("write_exec: Faild to kmalloc(pcol)\n");

		ret = -ENOMEM;

		goto err;

	}



	*pcol_copy = *pcol;



	osd_req_write(or, &obj, pcol_copy->bio, i_start);

	ret = exofs_async_op(or, writepages_done, pcol_copy, oi->i_cred);

	if (unlikely(ret)) {

		EXOFS_ERR("write_exec: exofs_async_op() Faild\n");

		goto err;

	}



	atomic_inc(&pcol->sbi->s_curr_pending);

	EXOFS_DBGMSG("write_exec(0x%lx, 0x%llx) start=0x%llx length=0x%lx\n",

		  pcol->inode->i_ino, pcol->pg_first, _LLU(i_start),

		  pcol->length);

	/* pages ownership was passed to pcol_copy */

	_pcol_reset(pcol);

	return 0;



err:

	_unlock_pcol_pages(pcol, ret, WRITE);

	kfree(pcol_copy);

	if (or)

		osd_end_request(or);

	return ret;

}



/* writepage_strip is called either directly from writepage() or by the VFS from

 * within write_cache_pages(), to add one more page to be written to storage.

 * It will try to collect as many contiguous pages as possible. If a

 * discontinuity is encountered or it runs out of resources it will submit the

 * previous segment and will start a new collection.

 * Eventually caller must submit the last segment if present.

 */

static int writepage_strip(struct page *page,

			   struct writeback_control *wbc_unused, void *data)

{

	struct page_collect *pcol = data;

	struct inode *inode = pcol->inode;

	struct exofs_i_info *oi = exofs_i(inode);

	loff_t i_size = i_size_read(inode);

	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;

	size_t len;

	int ret;



	BUG_ON(!PageLocked(page));



	ret = wait_obj_created(oi);

	if (unlikely(ret))

		goto fail;



	if (page->index < end_index)

		/* in this case, the page is within the limits of the file */

		len = PAGE_CACHE_SIZE;

	else {

		len = i_size & ~PAGE_CACHE_MASK;



		if (page->index > end_index || !len) {

			/* in this case, the page is outside the limits

			 * (truncate in progress)

			 */

			ret = write_exec(pcol);

			if (unlikely(ret))

				goto fail;

			if (PageError(page))

				ClearPageError(page);

			unlock_page(page);

			return 0;

		}

	}



try_again:



	if (unlikely(pcol->pg_first == -1)) {

		pcol->pg_first = page->index;

	} else if (unlikely((pcol->pg_first + pcol->nr_pages) !=

		   page->index)) {

		/* Discontinuity detected, split the request */

		ret = write_exec(pcol);

		if (unlikely(ret))

			goto fail;

		goto try_again;

	}



	if (!pcol->bio) {

		ret = pcol_try_alloc(pcol);

		if (unlikely(ret))

			goto fail;

	}



	EXOFS_DBGMSG("    writepage_strip(0x%lx, 0x%lx) len=0x%zx\n",

		     inode->i_ino, page->index, len);



	ret = pcol_add_page(pcol, page, len);

	if (unlikely(ret)) {

		EXOFS_DBGMSG("Failed pcol_add_page "

			     "nr_pages=%u total_length=0x%lx\n",

			     pcol->nr_pages, pcol->length);



		/* split the request, next loop will start again */

		ret = write_exec(pcol);

		if (unlikely(ret)) {

			EXOFS_DBGMSG("write_exec faild => %d", ret);

			goto fail;

		}



		goto try_again;

	}



	BUG_ON(PageWriteback(page));

	set_page_writeback(page);



	return 0;



fail:

	set_bit(AS_EIO, &page->mapping->flags);

	unlock_page(page);

	return ret;

}



static int exofs_writepages(struct address_space *mapping,

		       struct writeback_control *wbc)

{

	struct page_collect pcol;

	long start, end, expected_pages;

	int ret;



	start = wbc->range_start >> PAGE_CACHE_SHIFT;

	end = (wbc->range_end == LLONG_MAX) ?

			start + mapping->nrpages :

			wbc->range_end >> PAGE_CACHE_SHIFT;



	if (start || end)

		expected_pages = min(end - start + 1, 32L);

	else

		expected_pages = mapping->nrpages;



	EXOFS_DBGMSG("inode(0x%lx) wbc->start=0x%llx wbc->end=0x%llx"

		     " m->nrpages=%lu start=0x%lx end=0x%lx\n",

		     mapping->host->i_ino, wbc->range_start, wbc->range_end,

		     mapping->nrpages, start, end);



	_pcol_init(&pcol, expected_pages, mapping->host);



	ret = write_cache_pages(mapping, wbc, writepage_strip, &pcol);

	if (ret) {

		EXOFS_ERR("write_cache_pages => %d\n", ret);

		return ret;

	}



	return write_exec(&pcol);

}



static int exofs_writepage(struct page *page, struct writeback_control *wbc)

{

	struct page_collect pcol;

	int ret;



	_pcol_init(&pcol, 1, page->mapping->host);



	ret = writepage_strip(page, NULL, &pcol);

	if (ret) {

		EXOFS_ERR("exofs_writepage => %d\n", ret);

		return ret;

	}



	return write_exec(&pcol);

}



int exofs_write_begin(struct file *file, struct address_space *mapping,

		loff_t pos, unsigned len, unsigned flags,

		struct page **pagep, void **fsdata)

{

	int ret = 0;

	struct page *page;



	page = *pagep;

	if (page == NULL) {

		ret = simple_write_begin(file, mapping, pos, len, flags, pagep,

					 fsdata);

		if (ret) {

			EXOFS_DBGMSG("simple_write_begin faild\n");

			return ret;

		}



		page = *pagep;

	}



	 /* read modify write */

	if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {

		ret = _readpage(page, true);

		if (ret) {

			/*SetPageError was done by _readpage. Is it ok?*/

			unlock_page(page);

			EXOFS_DBGMSG("__readpage_filler faild\n");

		}

	}



	return ret;

}



static int exofs_write_begin_export(struct file *file,

		struct address_space *mapping,

		loff_t pos, unsigned len, unsigned flags,

		struct page **pagep, void **fsdata)

{

	*pagep = NULL;



	return exofs_write_begin(file, mapping, pos, len, flags, pagep,

					fsdata);

}



const struct address_space_operations exofs_aops = {

	.readpage	= exofs_readpage,

	.readpages	= exofs_readpages,

	.writepage	= exofs_writepage,

	.writepages	= exofs_writepages,

	.write_begin	= exofs_write_begin_export,

	.write_end	= simple_write_end,

};



/******************************************************************************

 * INODE OPERATIONS

 *****************************************************************************/

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