From b367e78bd1c7af4c018ce98b1f6d3e001aba895a Mon Sep 17 00:00:00 2001 From: Boaz Harrosh Date: Sun, 7 Feb 2010 19:18:58 +0200 Subject: 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: Boaz Harrosh --- fs/exofs/ios.c | 159 +++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 99 insertions(+), 60 deletions(-) (limited to 'fs/exofs') diff --git a/fs/exofs/ios.c b/fs/exofs/ios.c index 263052c..d28febd 100644 --- a/fs/exofs/ios.c +++ b/fs/exofs/ios.c @@ -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) -*/ - -static void _offset_dev_unit_off(struct exofs_io_state *ios, u64 file_offset, - u64 *obj_offset, unsigned *dev, unsigned *unit_off) +/* + * 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) + */ + +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; + + u32 LmodU; + u64 N = div_u64_rem(file_offset, U, &LmodU); - *unit_off = stripe_mod % stripe_unit; - *obj_offset = stripe_no * stripe_unit + *unit_off; - *dev = stripe_mod / stripe_unit * ios->layout->mirrors_p1; + 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; -- cgit v1.1