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, 2015, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
33 #define DEBUG_SUBSYSTEM S_LOV
35 #include <libcfs/libcfs.h>
37 #include <obd_class.h>
39 #include "lov_internal.h"
41 static loff_t stripe_width(struct lov_stripe_md *lsm, unsigned int index)
43 struct lov_stripe_md_entry *entry = lsm->lsm_entries[index];
45 LASSERT(index < lsm->lsm_entry_count);
47 return (loff_t)entry->lsme_stripe_size * entry->lsme_stripe_count;
50 /* compute object size given "stripeno" and the ost size */
51 u64 lov_stripe_size(struct lov_stripe_md *lsm, int index, u64 ost_size,
54 unsigned long ssize = lsm->lsm_entries[index]->lsme_stripe_size;
55 unsigned long stripe_size;
63 swidth = stripe_width(lsm, index);
65 /* lov_do_div64(a, b) returns a % b, and a = a / b */
66 stripe_size = lov_do_div64(ost_size, ssize);
68 lov_size = ost_size * swidth + stripeno * ssize + stripe_size;
70 lov_size = (ost_size - 1) * swidth + (stripeno + 1) * ssize;
76 * Compute file level page index by stripe level page offset
78 pgoff_t lov_stripe_pgoff(struct lov_stripe_md *lsm, int index,
79 pgoff_t stripe_index, int stripe)
83 offset = lov_stripe_size(lsm, index,
84 (stripe_index << PAGE_SHIFT) + 1,
86 return offset >> PAGE_SHIFT;
89 /* we have an offset in file backed by an lov and want to find out where
90 * that offset lands in our given stripe of the file. for the easy
91 * case where the offset is within the stripe, we just have to scale the
92 * offset down to make it relative to the stripe instead of the lov.
94 * the harder case is what to do when the offset doesn't intersect the
95 * stripe. callers will want start offsets clamped ahead to the start
96 * of the nearest stripe in the file. end offsets similarly clamped to the
97 * nearest ending byte of a stripe in the file:
99 * all this function does is move offsets to the nearest region of the
100 * stripe, and it does its work "mod" the full length of all the stripes.
101 * consider a file with 3 stripes:
104 * ---------------------------------------------------------------------
105 * | 0 | 1 | 2 | 0 | 1 | 2 |
106 * ---------------------------------------------------------------------
108 * to find stripe 1's offsets for S and E, it divides by the full stripe
109 * width and does its math in the context of a single set of stripes:
112 * -----------------------------------
114 * -----------------------------------
116 * it'll notice that E is outside stripe 1 and clamp it to the end of the
117 * stripe, then multiply it back out by lov_off to give the real offsets in
121 * ---------------------------------------------------------------------
122 * | 1 | 1 | 1 | 1 | 1 | 1 |
123 * ---------------------------------------------------------------------
125 * it would have done similarly and pulled S forward to the start of a 1
126 * stripe if, say, S had landed in a 0 stripe.
128 * this rounding isn't always correct. consider an E lov offset that lands
129 * on a 0 stripe, the "mod stripe width" math will pull it forward to the
130 * start of a 1 stripe, when in fact it wanted to be rounded back to the end
131 * of a previous 1 stripe. this logic is handled by callers and this is why:
133 * this function returns < 0 when the offset was "before" the stripe and
134 * was moved forward to the start of the stripe in question; 0 when it
135 * falls in the stripe and no shifting was done; > 0 when the offset
136 * was outside the stripe and was pulled back to its final byte. */
137 int lov_stripe_offset(struct lov_stripe_md *lsm, int index, loff_t lov_off,
138 int stripeno, loff_t *obdoff)
140 unsigned long ssize = lsm->lsm_entries[index]->lsme_stripe_size;
146 if (lov_off == OBD_OBJECT_EOF) {
147 *obdoff = OBD_OBJECT_EOF;
151 swidth = stripe_width(lsm, index);
153 /* lov_do_div64(a, b) returns a % b, and a = a / b */
154 stripe_off = lov_do_div64(lov_off, swidth);
156 this_stripe = (loff_t)stripeno * ssize;
157 if (stripe_off < this_stripe) {
161 stripe_off -= this_stripe;
163 if (stripe_off >= ssize) {
169 *obdoff = lov_off * ssize + stripe_off;
173 /* Given a whole-file size and a stripe number, give the file size which
174 * corresponds to the individual object of that stripe.
176 * This behaves basically in the same was as lov_stripe_offset, except that
177 * file sizes falling before the beginning of a stripe are clamped to the end
178 * of the previous stripe, not the beginning of the next:
181 * ---------------------------------------------------------------------
182 * | 0 | 1 | 2 | 0 | 1 | 2 |
183 * ---------------------------------------------------------------------
185 * if clamped to stripe 2 becomes:
188 * ---------------------------------------------------------------------
189 * | 0 | 1 | 2 | 0 | 1 | 2 |
190 * ---------------------------------------------------------------------
192 loff_t lov_size_to_stripe(struct lov_stripe_md *lsm, int index, u64 file_size,
195 unsigned long ssize = lsm->lsm_entries[index]->lsme_stripe_size;
200 if (file_size == OBD_OBJECT_EOF)
201 return OBD_OBJECT_EOF;
203 swidth = stripe_width(lsm, index);
205 /* lov_do_div64(a, b) returns a % b, and a = a / b */
206 stripe_off = lov_do_div64(file_size, swidth);
208 this_stripe = (loff_t)stripeno * ssize;
209 if (stripe_off < this_stripe) {
210 /* Move to end of previous stripe, or zero */
218 stripe_off -= this_stripe;
220 if (stripe_off >= ssize) {
221 /* Clamp to end of this stripe */
226 return (file_size * ssize + stripe_off);
229 /* given an extent in an lov and a stripe, calculate the extent of the stripe
230 * that is contained within the lov extent. this returns true if the given
231 * stripe does intersect with the lov extent. */
232 int lov_stripe_intersects(struct lov_stripe_md *lsm, int index, int stripeno,
233 struct lu_extent *ext, u64 *obd_start, u64 *obd_end)
235 struct lov_stripe_md_entry *entry = lsm->lsm_entries[index];
237 int start_side, end_side;
239 if (!lu_extent_is_overlapped(ext, &entry->lsme_extent))
242 start = max_t(__u64, ext->e_start, entry->lsme_extent.e_start);
243 end = min_t(__u64, ext->e_end, entry->lsme_extent.e_end);
244 if (end != OBD_OBJECT_EOF)
247 start_side = lov_stripe_offset(lsm, index, start, stripeno, obd_start);
248 end_side = lov_stripe_offset(lsm, index, end, stripeno, obd_end);
250 CDEBUG(D_INODE, "[%lld->%lld] -> [(%d) %lld->%lld (%d)]\n",
251 start, end, start_side, *obd_start, *obd_end, end_side);
253 /* this stripe doesn't intersect the file extent when neither
254 * start or the end intersected the stripe and obd_start and
255 * obd_end got rounded up to the save value. */
256 if (start_side != 0 && end_side != 0 && *obd_start == *obd_end)
259 /* as mentioned in the lov_stripe_offset commentary, end
260 * might have been shifted in the wrong direction. This
261 * happens when an end offset is before the stripe when viewed
262 * through the "mod stripe size" math. we detect it being shifted
263 * in the wrong direction and touch it up.
264 * interestingly, this can't underflow since end must be > start
265 * if we passed through the previous check.
266 * (should we assert for that somewhere?) */
273 /* compute which stripe number "lov_off" will be written into */
274 int lov_stripe_number(struct lov_stripe_md *lsm, int index, loff_t lov_off)
276 unsigned long ssize = lsm->lsm_entries[index]->lsme_stripe_size;
280 swidth = stripe_width(lsm, index);
282 stripe_off = lov_do_div64(lov_off, swidth);
284 /* Puts stripe_off/ssize result into stripe_off */
285 lov_do_div64(stripe_off, ssize);