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Commit b367e78b authored by Boaz Harrosh's avatar Boaz Harrosh
Browse files

exofs: Prepare for groups 



* Rename _offset_dev_unit_off() to _calc_stripe_info()
  and recieve a struct for the output params

* In _prepare_for_striping we only need to call
  _calc_stripe_info() once. The other componets
  are easy to calculate from that. This code
  was inspired by what's done in truncate.

* Some code shifts that make sense now but will make
  more sense when group support is added.

Signed-off-by: default avatarBoaz Harrosh <bharrosh@panasas.com>
parent 96391e2b

fs/exofs/ios.c

+99 −60
Original line number Diff line number Diff line
@@ -259,28 +259,46 @@ int exofs_check_io(struct exofs_io_state *ios, u64 *resid) 
	return acumulated_lin_err;

}



/* REMOVEME: After review

   Some quoteing from the standard



   L = logical offset into the file

   W = number of data components in a stripe

   S = W * stripe_unit (S is Stripe length)

   N = L / S (N is the stripe Number)

   C = (L-(N*S)) / stripe_unit (C is the component)

   O = (N*stripe_unit)+(L%stripe_unit) (O is the object's offset)

/*

 * L - logical offset into the file

 *

 * U - The number of bytes in a full stripe

 *

 *	U = stripe_unit * group_width

 *

 * N - The stripe number

 *

 *	N = L / U

 *

 * C - The component index coresponding to L

 *

 *	C = (L - (N*U)) / stripe_unit

 *

 * O - The component offset coresponding to L

 *

 *	(N*stripe_unit)+(L%stripe_unit)

 */



static void _offset_dev_unit_off(struct exofs_io_state *ios, u64 file_offset,

			u64 *obj_offset, unsigned *dev, unsigned *unit_off)

struct _striping_info {

	u64 obj_offset;

	unsigned dev;

	unsigned unit_off;

};



static void _calc_stripe_info(struct exofs_io_state *ios, u64 file_offset,

			      struct _striping_info *si)

{

	unsigned stripe_unit = ios->layout->stripe_unit;

	unsigned stripe_length = stripe_unit * ios->layout->group_width;

	u64 stripe_no = file_offset;

	unsigned stripe_mod = do_div(stripe_no, stripe_length);

	u32	stripe_unit = ios->layout->stripe_unit;

	u32	group_width = ios->layout->group_width;

	u32	U = stripe_unit * group_width;



	*unit_off = stripe_mod % stripe_unit;

	*obj_offset = stripe_no * stripe_unit + *unit_off;

	*dev = stripe_mod / stripe_unit * ios->layout->mirrors_p1;

	u32	LmodU;

	u64 	N = div_u64_rem(file_offset, U, &LmodU);



	si->unit_off = LmodU % stripe_unit;

	si->obj_offset = N * stripe_unit + si->unit_off;

	si->dev = LmodU / stripe_unit;

	si->dev *= ios->layout->mirrors_p1;

}



static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_pg,
@@ -327,65 +345,88 @@ static int _add_stripe_unit(struct exofs_io_state *ios, unsigned *cur_pg, 
	return 0;

}



static int _prepare_for_striping(struct exofs_io_state *ios)

static int _prepare_pages(struct exofs_io_state *ios,

			  struct _striping_info *si)

{

	u64 length = ios->length;

	u64 offset = ios->offset;

	unsigned stripe_unit = ios->layout->stripe_unit;

	unsigned mirrors_p1 = ios->layout->mirrors_p1;

	unsigned dev = si->dev;

	unsigned comp = 0;

	unsigned stripes = 0;

	unsigned cur_pg = 0;

	int ret = 0;



	if (!ios->pages) {

		if (ios->kern_buff) {

			struct exofs_per_dev_state *per_dev = &ios->per_dev[0];

			unsigned unit_off;



			_offset_dev_unit_off(ios, offset, &per_dev->offset,

					     &per_dev->dev, &unit_off);

			/* no cross device without page array */

			BUG_ON((ios->layout->group_width > 1) &&

			       (unit_off + length > stripe_unit));

		}

		ios->numdevs = ios->layout->mirrors_p1;

		return 0;

	}



	while (length) {

		struct exofs_per_dev_state *per_dev = &ios->per_dev[comp];

		unsigned cur_len, page_off;

		unsigned cur_len, page_off = 0;



		if (!per_dev->length) {

			unsigned unit_off;

			per_dev->dev = dev;

			if (dev < si->dev) {

				per_dev->offset = si->obj_offset + stripe_unit -

								   si->unit_off;

				cur_len = stripe_unit;

			} else if (dev == si->dev) {

				per_dev->offset = si->obj_offset;

				cur_len = stripe_unit - si->unit_off;

				page_off = si->unit_off & ~PAGE_MASK;

				BUG_ON(page_off && (page_off != ios->pgbase));

			} else { /* dev > si->dev */

				per_dev->offset = si->obj_offset - si->unit_off;

				cur_len = stripe_unit;

			}



			_offset_dev_unit_off(ios, offset, &per_dev->offset,

					     &per_dev->dev, &unit_off);

			stripes++;

			cur_len = min_t(u64, stripe_unit - unit_off, length);

			offset += cur_len;

			page_off = unit_off & ~PAGE_MASK;

			BUG_ON(page_off != ios->pgbase);



			dev += mirrors_p1;

			dev %= ios->layout->s_numdevs;

		} else {

			cur_len = min_t(u64, stripe_unit, length);

			page_off = 0;

			cur_len = stripe_unit;

		}

		if (cur_len >= length)

			cur_len = length;



		ret = _add_stripe_unit(ios, &cur_pg, page_off , per_dev,

				       cur_len);

		if (unlikely(ret))

			goto out;



		comp += ios->layout->mirrors_p1;

		comp += mirrors_p1;

		comp %= ios->layout->s_numdevs;



		length -= cur_len;

	}

out:

	ios->numdevs = stripes * ios->layout->mirrors_p1;

	ios->numdevs = stripes * mirrors_p1;

	return ret;

}



static int _prepare_for_striping(struct exofs_io_state *ios)

{

	struct _striping_info si;



	_calc_stripe_info(ios, ios->offset, &si);



	if (!ios->pages) {

		if (ios->kern_buff) {

			struct exofs_per_dev_state *per_dev = &ios->per_dev[0];



			per_dev->offset = si.obj_offset;

			per_dev->dev = si.dev;



			/* no cross device without page array */

			BUG_ON((ios->layout->group_width > 1) &&

			       (si.unit_off + ios->length >

				ios->layout->stripe_unit));

		}

		ios->numdevs = ios->layout->mirrors_p1;

		return 0;

	}



	return _prepare_pages(ios, &si);

}



int exofs_sbi_create(struct exofs_io_state *ios)

{

	int i, ret;
@@ -648,9 +689,7 @@ int exofs_oi_truncate(struct exofs_i_info *oi, u64 size) 
		struct osd_attr attr;

		__be64 newsize;

	} *size_attrs;

	u64 this_obj_size;

	unsigned dev;

	unsigned unit_off;

	struct _striping_info si;

	int i, ret;



	ret = exofs_get_io_state(&sbi->layout, &ios);
@@ -668,19 +707,19 @@ int exofs_oi_truncate(struct exofs_i_info *oi, u64 size) 
	ios->cred = oi->i_cred;



	ios->numdevs = ios->layout->s_numdevs;

	_offset_dev_unit_off(ios, size, &this_obj_size, &dev, &unit_off);

	_calc_stripe_info(ios, size, &si);



	for (i = 0; i < ios->layout->group_width; ++i) {

		struct exofs_trunc_attr *size_attr = &size_attrs[i];

		u64 obj_size;



		if (i < dev)

			obj_size = this_obj_size +

					ios->layout->stripe_unit - unit_off;

		else if (i == dev)

			obj_size = this_obj_size;

		else /* i > dev */

			obj_size = this_obj_size - unit_off;

		if (i < si.dev)

			obj_size = si.obj_offset +

					ios->layout->stripe_unit - si.unit_off;

		else if (i == si.dev)

			obj_size = si.obj_offset;

		else /* i > si.dev */

			obj_size = si.obj_offset - si.unit_off;



		size_attr->newsize = cpu_to_be64(obj_size);

		size_attr->attr = g_attr_logical_length;