4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2012, 2017, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
32 #define DEBUG_SUBSYSTEM S_LOV
34 #include <libcfs/libcfs.h>
36 #include <obd_class.h>
38 #include "lov_internal.h"
40 u64 stripe_width(struct lov_stripe_md *lsm, unsigned int index)
42 struct lov_stripe_md_entry *entry = lsm->lsm_entries[index];
44 LASSERT(index < lsm->lsm_entry_count);
46 if (lsme_is_dom(entry))
47 return entry->lsme_stripe_size;
49 return (u64)entry->lsme_stripe_size * entry->lsme_stripe_count;
52 /* compute object size given "stripeno" and the ost size */
53 u64 lov_stripe_size(struct lov_stripe_md *lsm, int index, u64 ost_size,
56 u32 ssize = lsm->lsm_entries[index]->lsme_stripe_size;
66 swidth = stripe_width(lsm, index);
68 ost_size = div_u64_rem(ost_size, ssize, &stripe_size);
70 lov_size = ost_size * swidth + stripeno * ssize + stripe_size;
72 lov_size = (ost_size - 1) * swidth + (stripeno + 1) * ssize;
78 * Compute file level page index by stripe level page offset
80 pgoff_t lov_stripe_pgoff(struct lov_stripe_md *lsm, int index,
81 pgoff_t stripe_index, int stripe)
85 offset = lov_stripe_size(lsm, index,
86 (stripe_index << PAGE_SHIFT) + 1,
88 return offset >> PAGE_SHIFT;
92 * we have an offset in file backed by an lov and want to find out where
93 * that offset lands in our given stripe of the file. for the easy
94 * case where the offset is within the stripe, we just have to scale the
95 * offset down to make it relative to the stripe instead of the lov.
97 * the harder case is what to do when the offset doesn't intersect the
98 * stripe. callers will want start offsets clamped ahead to the start
99 * of the nearest stripe in the file. end offsets similarly clamped to the
100 * nearest ending byte of a stripe in the file:
102 * all this function does is move offsets to the nearest region of the
103 * stripe, and it does its work "mod" the full length of all the stripes.
104 * consider a file with 3 stripes:
107 * ---------------------------------------------------------------------
108 * | 0 | 1 | 2 | 0 | 1 | 2 |
109 * ---------------------------------------------------------------------
111 * to find stripe 1's offsets for S and E, it divides by the full stripe
112 * width and does its math in the context of a single set of stripes:
115 * -----------------------------------
117 * -----------------------------------
119 * it'll notice that E is outside stripe 1 and clamp it to the end of the
120 * stripe, then multiply it back out by lov_off to give the real offsets in
124 * ---------------------------------------------------------------------
125 * | 1 | 1 | 1 | 1 | 1 | 1 |
126 * ---------------------------------------------------------------------
128 * it would have done similarly and pulled S forward to the start of a 1
129 * stripe if, say, S had landed in a 0 stripe.
131 * this rounding isn't always correct. consider an E lov offset that lands
132 * on a 0 stripe, the "mod stripe width" math will pull it forward to the
133 * start of a 1 stripe, when in fact it wanted to be rounded back to the end
134 * of a previous 1 stripe. this logic is handled by callers and this is why:
136 * this function returns < 0 when the offset was "before" the stripe and
137 * was moved forward to the start of the stripe in question; 0 when it
138 * falls in the stripe and no shifting was done; > 0 when the offset
139 * was outside the stripe and was pulled back to its final byte.
141 int lov_stripe_offset(struct lov_stripe_md *lsm, int index, loff_t lov_off,
142 int stripeno, loff_t *obdoff)
144 unsigned long ssize = lsm->lsm_entries[index]->lsme_stripe_size;
145 u64 stripe_off, this_stripe, swidth;
148 if (lov_off == OBD_OBJECT_EOF) {
149 *obdoff = OBD_OBJECT_EOF;
153 swidth = stripe_width(lsm, index);
155 lov_off = div64_u64_rem(lov_off, swidth, &stripe_off);
157 this_stripe = (u64)stripeno * ssize;
158 if (stripe_off < this_stripe) {
162 stripe_off -= this_stripe;
164 if (stripe_off >= ssize) {
170 *obdoff = lov_off * ssize + stripe_off;
175 * Given a whole-file size and a stripe number, give the file size which
176 * corresponds to the individual object of that stripe.
178 * This behaves basically in the same was as lov_stripe_offset, except that
179 * file sizes falling before the beginning of a stripe are clamped to the end
180 * of the previous stripe, not the beginning of the next:
183 * ---------------------------------------------------------------------
184 * | 0 | 1 | 2 | 0 | 1 | 2 |
185 * ---------------------------------------------------------------------
187 * if clamped to stripe 2 becomes:
190 * ---------------------------------------------------------------------
191 * | 0 | 1 | 2 | 0 | 1 | 2 |
192 * ---------------------------------------------------------------------
194 loff_t lov_size_to_stripe(struct lov_stripe_md *lsm, int index, u64 file_size,
197 unsigned long ssize = lsm->lsm_entries[index]->lsme_stripe_size;
202 if (file_size == OBD_OBJECT_EOF)
203 return OBD_OBJECT_EOF;
205 swidth = stripe_width(lsm, index);
207 file_size = div64_u64_rem(file_size, swidth, &stripe_off);
209 this_stripe = (u64)stripeno * ssize;
210 if (stripe_off < this_stripe) {
211 /* Move to end of previous stripe, or zero */
219 stripe_off -= this_stripe;
221 if (stripe_off >= ssize) {
222 /* Clamp to end of this stripe */
227 return (file_size * ssize + stripe_off);
231 * given an extent in an lov and a stripe, calculate the extent of the stripe
232 * that is contained within the lov extent. this returns true if the given
233 * stripe does intersect with the lov extent.
235 * Closed interval [@obd_start, @obd_end] will be returned if caller needs them.
237 int lov_stripe_intersects(struct lov_stripe_md *lsm, int index, int stripeno,
238 struct lu_extent *ext, u64 *obd_start, u64 *obd_end)
240 struct lov_stripe_md_entry *entry = lsm->lsm_entries[index];
242 int start_side, end_side;
243 u64 loc_start, loc_end;
245 if (!lu_extent_is_overlapped(ext, &entry->lsme_extent))
249 obd_start = &loc_start;
253 start = max_t(__u64, ext->e_start, entry->lsme_extent.e_start);
254 end = min_t(__u64, ext->e_end, entry->lsme_extent.e_end);
255 if (end != OBD_OBJECT_EOF)
258 start_side = lov_stripe_offset(lsm, index, start, stripeno, obd_start);
259 end_side = lov_stripe_offset(lsm, index, end, stripeno, obd_end);
261 CDEBUG(D_INODE, "[%lld->%lld] -> [(%d) %lld->%lld (%d)]\n",
262 start, end, start_side, *obd_start, *obd_end, end_side);
265 * this stripe doesn't intersect the file extent when neither
266 * start or the end intersected the stripe and obd_start and
267 * obd_end got rounded up to the save value.
269 if (start_side != 0 && end_side != 0 && *obd_start == *obd_end)
273 * as mentioned in the lov_stripe_offset commentary, end
274 * might have been shifted in the wrong direction. This
275 * happens when an end offset is before the stripe when viewed
276 * through the "mod stripe size" math. we detect it being shifted
277 * in the wrong direction and touch it up.
278 * interestingly, this can't underflow since end must be > start
279 * if we passed through the previous check.
280 * (should we assert for that somewhere?)
288 /* compute which stripe number "lov_off" will be written into */
289 int lov_stripe_number(struct lov_stripe_md *lsm, int index, u64 lov_off)
291 unsigned long ssize = lsm->lsm_entries[index]->lsme_stripe_size;
295 swidth = stripe_width(lsm, index);
297 lov_off = div64_u64_rem(lov_off, swidth, &stripe_off);
299 /* Puts stripe_off/ssize result into stripe_off */
300 stripe_off = div_u64(stripe_off, ssize);
302 return (int) stripe_off;