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exofs: groups support
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* _calc_stripe_info() changes to accommodate for grouping
  calculations. Returns additional information

* old _prepare_pages() becomes _prepare_one_group()
  which stores pages belonging to one device group.

* New _prepare_for_striping iterates on all groups calling
  _prepare_one_group().

* Enable mounting of groups data_maps (group_width != 0)

[QUESTION]
what is faster A or B;
A.	x += stride;
	x = x % width + first_x;

B	x += stride
	if (x < last_x)
		x = first_x;

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
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Boaz Harrosh committed Feb 28, 2010
1 parent b367e78 commit 50a76fd
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Showing 3 changed files with 141 additions and 37 deletions.
3 changes: 3 additions & 0 deletions fs/exofs/exofs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,8 @@ struct exofs_layout {
unsigned mirrors_p1;

unsigned group_width;
u64 group_depth;
unsigned group_count;

enum exofs_inode_layout_gen_functions lay_func;

Expand Down Expand Up @@ -132,6 +134,7 @@ struct exofs_io_state {
struct page **pages;
unsigned nr_pages;
unsigned pgbase;
unsigned pages_consumed;

/* Attributes */
unsigned in_attr_len;
Expand Down
129 changes: 106 additions & 23 deletions fs/exofs/ios.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -262,25 +262,50 @@ int exofs_check_io(struct exofs_io_state *ios, u64 *resid)
/*
* L - logical offset into the file
*
* U - The number of bytes in a full stripe
* U - The number of bytes in a stripe within a group
*
* U = stripe_unit * group_width
*
* N - The stripe number
* T - The number of bytes striped within a group of component objects
* (before advancing to the next group)
*
* N = L / U
* T = stripe_unit * group_width * group_depth
*
* S - The number of bytes striped across all component objects
* before the pattern repeats
*
* S = stripe_unit * group_width * group_depth * group_count
*
* M - The "major" (i.e., across all components) stripe number
*
* M = L / S
*
* G - Counts the groups from the beginning of the major stripe
*
* G = (L - (M * S)) / T [or (L % S) / T]
*
* H - The byte offset within the group
*
* H = (L - (M * S)) % T [or (L % S) % T]
*
* N - The "minor" (i.e., across the group) stripe number
*
* N = H / U
*
* C - The component index coresponding to L
*
* C = (L - (N*U)) / stripe_unit
* C = (H - (N * U)) / stripe_unit + G * group_width
* [or (L % U) / stripe_unit + G * group_width]
*
* O - The component offset coresponding to L
*
* (N*stripe_unit)+(L%stripe_unit)
* O = L % stripe_unit + N * stripe_unit + M * group_depth * stripe_unit
*/

struct _striping_info {
u64 obj_offset;
u64 group_length;
u64 total_group_length;
u64 Major;
unsigned dev;
unsigned unit_off;
};
Expand All @@ -290,15 +315,35 @@ static void _calc_stripe_info(struct exofs_io_state *ios, u64 file_offset,
{
u32 stripe_unit = ios->layout->stripe_unit;
u32 group_width = ios->layout->group_width;
u64 group_depth = ios->layout->group_depth;

u32 U = stripe_unit * group_width;
u64 T = U * group_depth;
u64 S = T * ios->layout->group_count;
u64 M = div64_u64(file_offset, S);

/*
G = (L - (M * S)) / T
H = (L - (M * S)) % T
*/
u64 LmodS = file_offset - M * S;
u32 G = div64_u64(LmodS, T);
u64 H = LmodS - G * T;

u32 N = div_u64(H, U);

/* "H - (N * U)" is just "H % U" so it's bound to u32 */
si->dev = (u32)(H - (N * U)) / stripe_unit + G * group_width;
si->dev *= ios->layout->mirrors_p1;

u32 LmodU;
u64 N = div_u64_rem(file_offset, U, &LmodU);
div_u64_rem(file_offset, stripe_unit, &si->unit_off);

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;
si->obj_offset = si->unit_off + (N * stripe_unit) +
(M * group_depth * stripe_unit);

si->group_length = T - H;
si->total_group_length = T;
si->Major = M;
}

static int _add_stripe_unit(struct exofs_io_state *ios, unsigned *cur_pg,
Expand Down Expand Up @@ -345,16 +390,17 @@ static int _add_stripe_unit(struct exofs_io_state *ios, unsigned *cur_pg,
return 0;
}

static int _prepare_pages(struct exofs_io_state *ios,
struct _striping_info *si)
static int _prepare_one_group(struct exofs_io_state *ios, u64 length,
struct _striping_info *si, unsigned first_comp)
{
u64 length = ios->length;
unsigned stripe_unit = ios->layout->stripe_unit;
unsigned mirrors_p1 = ios->layout->mirrors_p1;
unsigned devs_in_group = ios->layout->group_width * mirrors_p1;
unsigned dev = si->dev;
unsigned comp = 0;
unsigned stripes = 0;
unsigned cur_pg = 0;
unsigned first_dev = dev - (dev % devs_in_group);
unsigned comp = first_comp + (dev - first_dev);
unsigned max_comp = ios->numdevs ? ios->numdevs - mirrors_p1 : 0;
unsigned cur_pg = ios->pages_consumed;
int ret = 0;

while (length) {
Expand All @@ -377,10 +423,11 @@ static int _prepare_pages(struct exofs_io_state *ios,
cur_len = stripe_unit;
}

stripes++;
if (max_comp < comp)
max_comp = comp;

dev += mirrors_p1;
dev %= ios->layout->s_numdevs;
dev = (dev % devs_in_group) + first_dev;
} else {
cur_len = stripe_unit;
}
Expand All @@ -393,18 +440,24 @@ static int _prepare_pages(struct exofs_io_state *ios,
goto out;

comp += mirrors_p1;
comp %= ios->layout->s_numdevs;
comp = (comp % devs_in_group) + first_comp;

length -= cur_len;
}
out:
ios->numdevs = stripes * mirrors_p1;
ios->numdevs = max_comp + mirrors_p1;
ios->pages_consumed = cur_pg;
return ret;
}

static int _prepare_for_striping(struct exofs_io_state *ios)
{
u64 length = ios->length;
struct _striping_info si;
unsigned devs_in_group = ios->layout->group_width *
ios->layout->mirrors_p1;
unsigned first_comp = 0;
int ret = 0;

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

Expand All @@ -424,7 +477,31 @@ static int _prepare_for_striping(struct exofs_io_state *ios)
return 0;
}

return _prepare_pages(ios, &si);
while (length) {
if (length < si.group_length)
si.group_length = length;

ret = _prepare_one_group(ios, si.group_length, &si, first_comp);
if (unlikely(ret))
goto out;

length -= si.group_length;

si.group_length = si.total_group_length;
si.unit_off = 0;
++si.Major;
si.obj_offset = si.Major * ios->layout->stripe_unit *
ios->layout->group_depth;

si.dev = (si.dev - (si.dev % devs_in_group)) + devs_in_group;
si.dev %= ios->layout->s_numdevs;

first_comp += devs_in_group;
first_comp %= ios->layout->s_numdevs;
}

out:
return ret;
}

int exofs_sbi_create(struct exofs_io_state *ios)
Expand Down Expand Up @@ -482,6 +559,9 @@ static int _sbi_write_mirror(struct exofs_io_state *ios, int cur_comp)
unsigned last_comp = cur_comp + ios->layout->mirrors_p1;
int ret = 0;

if (ios->pages && !master_dev->length)
return 0; /* Just an empty slot */

for (; cur_comp < last_comp; ++cur_comp, ++dev) {
struct exofs_per_dev_state *per_dev = &ios->per_dev[cur_comp];
struct osd_request *or;
Expand Down Expand Up @@ -580,6 +660,9 @@ static int _sbi_read_mirror(struct exofs_io_state *ios, unsigned cur_comp)
struct exofs_per_dev_state *per_dev = &ios->per_dev[cur_comp];
unsigned first_dev = (unsigned)ios->obj.id;

if (ios->pages && !per_dev->length)
return 0; /* Just an empty slot */

first_dev = per_dev->dev + first_dev % ios->layout->mirrors_p1;
or = osd_start_request(exofs_ios_od(ios, first_dev), GFP_KERNEL);
if (unlikely(!or)) {
Expand Down
46 changes: 32 additions & 14 deletions fs/exofs/super.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -323,11 +323,7 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
sbi->data_map.odm_raid_algorithm =
le32_to_cpu(dt->dt_data_map.cb_raid_algorithm);

/* FIXME: Only raid0 !group_width/depth for now. if not so, do not mount */
if (sbi->data_map.odm_group_width || sbi->data_map.odm_group_depth) {
EXOFS_ERR("Group width/depth not supported\n");
return -EINVAL;
}
/* FIXME: Only raid0 for now. if not so, do not mount */
if (sbi->data_map.odm_num_comps != numdevs) {
EXOFS_ERR("odm_num_comps(%u) != numdevs(%u)\n",
sbi->data_map.odm_num_comps, numdevs);
Expand All @@ -343,14 +339,6 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
return -EINVAL;
}

stripe_length = sbi->data_map.odm_stripe_unit *
(numdevs / (sbi->data_map.odm_mirror_cnt + 1));
if (stripe_length >= (1ULL << 32)) {
EXOFS_ERR("Total Stripe length(0x%llx)"
" >= 32bit is not supported\n", _LLU(stripe_length));
return -EINVAL;
}

if (0 != (sbi->data_map.odm_stripe_unit & ~PAGE_MASK)) {
EXOFS_ERR("Stripe Unit(0x%llx)"
" must be Multples of PAGE_SIZE(0x%lx)\n",
Expand All @@ -360,8 +348,36 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,

sbi->layout.stripe_unit = sbi->data_map.odm_stripe_unit;
sbi->layout.mirrors_p1 = sbi->data_map.odm_mirror_cnt + 1;
sbi->layout.group_width = sbi->data_map.odm_num_comps /

if (sbi->data_map.odm_group_width) {
sbi->layout.group_width = sbi->data_map.odm_group_width;
sbi->layout.group_depth = sbi->data_map.odm_group_depth;
if (!sbi->layout.group_depth) {
EXOFS_ERR("group_depth == 0 && group_width != 0\n");
return -EINVAL;
}
sbi->layout.group_count = sbi->data_map.odm_num_comps /
sbi->layout.mirrors_p1 /
sbi->data_map.odm_group_width;
} else {
if (sbi->data_map.odm_group_depth) {
printk(KERN_NOTICE "Warning: group_depth ignored "
"group_width == 0 && group_depth == %d\n",
sbi->data_map.odm_group_depth);
sbi->data_map.odm_group_depth = 0;
}
sbi->layout.group_width = sbi->data_map.odm_num_comps /
sbi->layout.mirrors_p1;
sbi->layout.group_depth = -1;
sbi->layout.group_count = 1;
}

stripe_length = (u64)sbi->layout.group_width * sbi->layout.stripe_unit;
if (stripe_length >= (1ULL << 32)) {
EXOFS_ERR("Total Stripe length(0x%llx)"
" >= 32bit is not supported\n", _LLU(stripe_length));
return -EINVAL;
}

return 0;
}
Expand Down Expand Up @@ -540,6 +556,8 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
sbi->layout.stripe_unit = PAGE_SIZE;
sbi->layout.mirrors_p1 = 1;
sbi->layout.group_width = 1;
sbi->layout.group_depth = -1;
sbi->layout.group_count = 1;
sbi->layout.s_ods[0] = od;
sbi->layout.s_numdevs = 1;
sbi->layout.s_pid = opts->pid;
Expand Down

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