/* $NetBSD: subr_extent.c,v 1.4 1996/10/10 22:46:25 christos Exp $ */ /*- * Copyright (c) 1996 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe and Matthias Drochner. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * General purpose extent manager. */ #include #include #include #include #include #include static int extent_insert_and_optimize __P((struct extent *, u_long, u_long, int, struct extent_region *)); static struct extent_region *extent_alloc_region_descriptor __P((struct extent *, int)); static void extent_free_region_descriptor __P((struct extent *, struct extent_region *)); /* * Allocate and initialize an extent map. */ struct extent * extent_create(name, start, end, mtype, storage, storagesize, flags) char *name; u_long start, end; int mtype; caddr_t storage; size_t storagesize; int flags; { struct extent *ex; caddr_t cp = storage; size_t sz = storagesize; struct extent_region *rp; int fixed_extent = (storage != NULL); /* Check arguments. */ if (name == NULL) panic("extent_create: name == NULL"); if (end < start) { kprintf("extent_create: extent `%s', start 0x%lx, end 0x%lx\n", name, start, end); panic("extent_create: end < start"); } if (fixed_extent && (storagesize < sizeof(struct extent_fixed))) panic("extent_create: fixed extent, bad storagesize 0x%x", storagesize); /* Allocate extent descriptor. */ if (fixed_extent) { struct extent_fixed *fex; bzero(storage, storagesize); /* * Align all descriptors on "long" boundaries. */ fex = (struct extent_fixed *)cp; ex = (struct extent *)fex; cp += EXTENT_ALIGN(sizeof(struct extent_fixed), sizeof(long)); sz -= EXTENT_ALIGN(sizeof(struct extent_fixed), sizeof(long)); fex->fex_storage = storage; fex->fex_storagesize = storagesize; /* * In a fixed extent, we have to pre-allocate region * descriptors and place them in the extent's freelist. */ LIST_INIT(&fex->fex_freelist); while (sz >= sizeof(struct extent_region)) { rp = (struct extent_region *)cp; cp += EXTENT_ALIGN(sizeof(struct extent_region), sizeof(long)); sz -= EXTENT_ALIGN(sizeof(struct extent_region), sizeof(long)); LIST_INSERT_HEAD(&fex->fex_freelist, rp, er_link); } } else { ex = (struct extent *)malloc(sizeof(struct extent), mtype, (flags & EX_WAITOK) ? M_WAITOK : M_NOWAIT); if (ex == NULL) return (NULL); } /* Fill in the extent descriptor and return it to the caller. */ LIST_INIT(&ex->ex_regions); ex->ex_name = name; ex->ex_start = start; ex->ex_end = end; ex->ex_mtype = mtype; ex->ex_flags = 0; if (fixed_extent) ex->ex_flags |= EXF_FIXED; if (flags & EX_NOBLOB) ex->ex_flags |= EXF_NOBLOB; return (ex); } /* * Destroy an extent map. */ void extent_destroy(ex) struct extent *ex; { struct extent_region *rp, *orp; int mtype; /* Check arguments. */ if (ex == NULL) panic("extent_destroy: NULL extent"); mtype = ex->ex_mtype; /* Free all region descriptors in extent. */ for (rp = ex->ex_regions.lh_first; rp != NULL; ) { orp = rp; rp = rp->er_link.le_next; LIST_REMOVE(orp, er_link); extent_free_region_descriptor(ex, orp); } /* If we're not a fixed extent, free the extent descriptor itself. */ if ((ex->ex_flags & EXF_FIXED) == 0) free(ex, mtype); } /* * Insert a region descriptor into the sorted region list after the * entry "after" or at the head of the list (if "after" is NULL). */ static int extent_insert_and_optimize(ex, start, size, flags, after) struct extent *ex; u_long start, size; int flags; struct extent_region *after; { struct extent_region *rp; int appended = 0; if (after == NULL) { /* * We're the first in the region list. If there's * a region after us, attempt to coalesce to save * descriptor overhead. */ if (((ex->ex_flags & EXF_NOBLOB) == 0) && (ex->ex_regions.lh_first != NULL) && ((start + size) == ex->ex_regions.lh_first->er_start)) { /* * We can coalesce. Prepend us to the first region. */ ex->ex_regions.lh_first->er_start = start; return (0); } /* * Can't coalesce. Allocate a region descriptor, fill it * in, and insert us at the head of the region list. */ rp = extent_alloc_region_descriptor(ex, flags); if (rp == NULL) { #if defined(DEBUG) || defined(DIAGNOSTIC) kprintf("extent `%s': can't alloc region descriptor.\n", ex->ex_name); #endif return (ENOMEM); } rp->er_start = start; rp->er_end = start + (size - 1); LIST_INSERT_HEAD(&ex->ex_regions, rp, er_link); return (0); } /* * If EXF_NOBLOB is set, coalescing is disallowed. */ if (ex->ex_flags & EXF_NOBLOB) goto allocate_region_descriptor; /* * Attempt to coalesce with the region before us. */ if ((after->er_end + 1) == start) { /* * We can coalesce. Append ourselves and make * note of it. */ after->er_end = start + (size - 1); appended = 1; } /* * Attempt to coalesce with the region after us. */ if ((after->er_link.le_next != NULL) && ((start + size) == after->er_link.le_next->er_start)) { /* * We can coalesce. Note that if we appended ourselves * to the previous region, we exactly fit the gap, and * can free the "next" region descriptor. */ if (appended) { /* * Yup, we can free it up. */ after->er_end = after->er_link.le_next->er_end; LIST_REMOVE(after->er_link.le_next, er_link); extent_free_region_descriptor(ex, after->er_link.le_next); } else { /* * Nope, just prepend us to the next region. */ after->er_link.le_next->er_start = start; } return (0); } /* * We weren't able to coalesce with the next region, but * we don't need to allocate a region descriptor if we * appended ourselves to the previous region. */ if (appended) return (0); allocate_region_descriptor: /* * Allocate a region descriptor and insert ourselves * into the region list. */ rp = extent_alloc_region_descriptor(ex, flags); if (rp == NULL) { #if defined(DEBUG) || defined(DIAGNOSTIC) kprintf("extent `%s': can't allocate region descriptor.\n", ex->ex_name); #endif return (ENOMEM); } rp->er_start = start; rp->er_end = start + (size - 1); LIST_INSERT_AFTER(after, rp, er_link); return (0); } /* * Allocate a specific region in an extent map. */ int extent_alloc_region(ex, start, size, flags) struct extent *ex; u_long start, size; int flags; { struct extent_region *rp, *last; u_long end = start + (size - 1); int error; /* Check arguments. */ if (ex == NULL) panic("extent_alloc_region: NULL extent"); if (size < 1) { kprintf("extent_alloc_region: extent `%s', size 0x%lx\n", ex->ex_name, size); panic("extent_alloc_region: bad size"); } if (end < start) { kprintf( "extent_alloc_region: extent `%s', start 0x%lx, size 0x%lx\n", ex->ex_name, start, size); panic("extent_alloc_region: overflow"); } /* * Make sure the requested region lies within the * extent. */ if ((start < ex->ex_start) || (end > ex->ex_end)) { kprintf("extent_alloc_region: extent `%s' (0x%lx - 0x%lx)\n", ex->ex_name, ex->ex_start, ex->ex_end); kprintf("extent_alloc_region: start 0x%lx, end 0x%lx\n", start, end); panic("extent_alloc_region: region lies outside extent"); } alloc_start: /* * Attempt to place ourselves in the desired area of the * extent. We save ourselves some work by keeping the list sorted. * In other words, if the start of the current region is greater * than the end of our region, we don't have to search any further. */ /* * Keep a pointer to the last region we looked at so * that we don't have to traverse the list again when * we insert ourselves. If "last" is NULL when we * finally insert ourselves, we go at the head of the * list. See extent_insert_and_optimize() for details. */ last = NULL; for (rp = ex->ex_regions.lh_first; rp != NULL; rp = rp->er_link.le_next) { if (rp->er_start > end) { /* * We lie before this region and don't * conflict. */ break; } /* * The current region begins before we end. * Check for a conflict. */ if (rp->er_end >= start) { /* * We conflict. If we can wait, do so. */ if (flags & EX_WAITOK) { ex->ex_flags |= EXF_WANTED; error = tsleep(ex, PRIBIO | ((flags & EX_CATCH) ? PCATCH : 0), "extnt", 0); if (error) return (error); goto alloc_start; } return (EAGAIN); } /* * We don't conflict, but this region lies before * us. Keep a pointer to this region, and keep * trying. */ last = rp; } /* * We don't conflict with any regions. "last" points * to the region we fall after, or is NULL if we belong * at the beginning of the region list. Insert ourselves. */ return (extent_insert_and_optimize(ex, start, size, flags, last)); } /* * Macro to check (x + y) <= z. This check is designed to fail * if an overflow occurs. */ #define LE_OV(x, y, z) ((((x) + (y)) >= (x)) && (((x) + (y)) <= (z))) /* * Allocate a region in an extent map subregion. * * If EX_FAST is specified, we return the first fit in the map. * Otherwise, we try to minimize fragmentation by finding the * smallest gap that will hold the request. * * The allocated region is aligned to "alignment", which must be * a power of 2. */ int extent_alloc_subregion(ex, substart, subend, size, alignment, boundary, flags, result) struct extent *ex; u_long substart, subend, size, alignment, boundary; int flags; u_long *result; { struct extent_region *rp, *last, *bestlast; u_long newstart, newend, beststart, bestovh, ovh; u_long dontcross, odontcross; int error; /* Check arguments. */ if (ex == NULL) panic("extent_alloc_subregion: NULL extent"); if (result == NULL) panic("extent_alloc_subregion: NULL result pointer"); if ((substart < ex->ex_start) || (substart >= ex->ex_end) || (subend > ex->ex_end) || (subend <= ex->ex_start)) { kprintf("extent_alloc_subregion: extent `%s', ex_start 0x%lx, ex_end 0x%lx\n", ex->ex_name, ex->ex_start, ex->ex_end); kprintf("extent_alloc_subregion: substart 0x%lx, subend 0x%lx\n", substart, subend); panic("extent_alloc_subregion: bad subregion"); } if ((size < 1) || (size > ((subend - substart) + 1))) { kprintf("extent_alloc_subregion: extent `%s', size 0x%lx\n", ex->ex_name, size); panic("extent_alloc_subregion: bad size"); } if (alignment == 0) panic("extent_alloc_subregion: bad alignment"); if (boundary && (boundary < size)) { kprintf( "extent_alloc_subregion: extent `%s', size 0x%lx, boundary 0x%lx\n", ex->ex_name, size, boundary); panic("extent_alloc_subregion: bad boundary"); } alloc_start: /* * Keep a pointer to the last region we looked at so * that we don't have to traverse the list again when * we insert ourselves. If "last" is NULL when we * finally insert ourselves, we go at the head of the * list. See extent_insert_and_optimize() for deatails. */ last = NULL; /* * Initialize the "don't cross" boundary, a.k.a a line * that a region should not cross. If the boundary lies * before the region starts, we add the "boundary" argument * until we get a meaningful comparison. */ dontcross = 0; if (boundary) { dontcross = ex->ex_start + boundary; while (dontcross < substart) dontcross += boundary; } /* * Keep track of size and location of the smallest * chunk we fit in. * * Since the extent can be as large as the numeric range * of the CPU (0 - 0xffffffff for 32-bit systems), the * best overhead value can be the maximum unsigned integer. * Thus, we initialize "bestovh" to 0, since we insert ourselves * into the region list immediately on an exact match (which * is the only case where "bestovh" would be set to 0). */ bestovh = 0; beststart = 0; bestlast = NULL; /* * For N allocated regions, we must make (N + 1) * checks for unallocated space. The first chunk we * check is the area from the beginning of the subregion * to the first allocated region. */ newstart = EXTENT_ALIGN(substart, alignment); if (newstart < ex->ex_start) { kprintf( "extent_alloc_subregion: extent `%s' (0x%lx - 0x%lx), alignment 0x%lx\n", ex->ex_name, ex->ex_start, ex->ex_end, alignment); panic("extent_alloc_subregion: overflow after alignment"); } for (rp = ex->ex_regions.lh_first; rp != NULL; rp = rp->er_link.le_next) { /* * Check the chunk before "rp". Note that our * comparison is safe from overflow conditions. */ if (LE_OV(newstart, size, rp->er_start)) { /* * Do a boundary check, if necessary. Note * that a region may *begin* on the boundary, * but it must end before the boundary. */ if (boundary) { newend = newstart + (size - 1); /* * Adjust boundary for a meaningful * comparison. */ while (dontcross <= newstart) { odontcross = dontcross; dontcross += boundary; /* * If we run past the end of * the extent or the boundary * overflows, then the request * can't fit. */ if ((dontcross > ex->ex_end) || (dontcross < odontcross)) goto fail; } /* Do the boundary check. */ if (newend >= dontcross) { /* * Candidate region crosses * boundary. Try again. */ continue; } } /* * We would fit into this space. Calculate * the overhead (wasted space). If we exactly * fit, or we're taking the first fit, insert * ourselves into the region list. */ ovh = rp->er_start - newstart - size; if ((flags & EX_FAST) || (ovh == 0)) goto found; /* * Don't exactly fit, but check to see * if we're better than any current choice. */ if ((bestovh == 0) || (ovh < bestovh)) { bestovh = ovh; beststart = newstart; bestlast = last; } } /* * Skip past the current region and check again. */ newstart = EXTENT_ALIGN((rp->er_end + 1), alignment); if (newstart < rp->er_end) { /* * Overflow condition. Don't error out, since * we might have a chunk of space that we can * use. */ goto fail; } last = rp; } /* * The final check is from the current starting point to the * end of the subregion. If there were no allocated regions, * "newstart" is set to the beginning of the subregion, or * just past the end of the last allocated region, adjusted * for alignment in either case. */ if (LE_OV(newstart, (size - 1), subend)) { /* * We would fit into this space. Calculate * the overhead (wasted space). If we exactly * fit, or we're taking the first fit, insert * ourselves into the region list. */ ovh = ex->ex_end - newstart - (size - 1); if ((flags & EX_FAST) || (ovh == 0)) goto found; /* * Don't exactly fit, but check to see * if we're better than any current choice. */ if ((bestovh == 0) || (ovh < bestovh)) { bestovh = ovh; beststart = newstart; bestlast = last; } } fail: /* * One of the following two conditions have * occurred: * * There is no chunk large enough to hold the request. * * If EX_FAST was not specified, there is not an * exact match for the request. * * Note that if we reach this point and EX_FAST is * set, then we know there is no space in the extent for * the request. */ if (((flags & EX_FAST) == 0) && (bestovh != 0)) { /* * We have a match that's "good enough". */ newstart = beststart; last = bestlast; goto found; } /* * No space currently available. Wait for it to free up, * if possible. */ if (flags & EX_WAITOK) { ex->ex_flags |= EXF_WANTED; error = tsleep(ex, PRIBIO | ((flags & EX_CATCH) ? PCATCH : 0), "extnt", 0); if (error) return (error); goto alloc_start; } return (EAGAIN); found: /* * Insert ourselves into the region list. */ error = extent_insert_and_optimize(ex, newstart, size, flags, last); if (error == 0) *result = newstart; return (error); } int extent_free(ex, start, size, flags) struct extent *ex; u_long start, size; int flags; { struct extent_region *rp; u_long end = start + (size - 1); /* Check arguments. */ if (ex == NULL) panic("extent_free: NULL extent"); if ((start < ex->ex_start) || (start > ex->ex_end)) { extent_print(ex); kprintf("extent_free: extent `%s', start 0x%lx, size 0x%lx\n", ex->ex_name, start, size); panic("extent_free: extent `%s', region not within extent", ex->ex_name); } /* Check for an overflow. */ if (end < start) { extent_print(ex); kprintf("extent_free: extent `%s', start 0x%lx, size 0x%lx\n", ex->ex_name, start, size); panic("extent_free: overflow"); } /* * Find region and deallocate. Several possibilities: * * 1. (start == er_start) && (end == er_end): * Free descriptor. * * 2. (start == er_start) && (end < er_end): * Adjust er_start. * * 3. (start > er_start) && (end == er_end): * Adjust er_end. * * 4. (start > er_start) && (end < er_end): * Fragment region. Requires descriptor alloc. * * Cases 2, 3, and 4 require that the EXF_NOBLOB flag * is not set. */ for (rp = ex->ex_regions.lh_first; rp != NULL; rp = rp->er_link.le_next) { /* * Save ourselves some comparisons; does the current * region end before chunk to be freed begins? If so, * then we haven't found the appropriate region descriptor. */ if (rp->er_end < start) continue; /* * Save ourselves some traversal; does the current * region begin after the chunk to be freed ends? If so, * then we've already passed any possible region descriptors * that might have contained the chunk to be freed. */ if (rp->er_start > end) break; /* Case 1. */ if ((start == rp->er_start) && (end == rp->er_end)) { LIST_REMOVE(rp, er_link); extent_free_region_descriptor(ex, rp); goto done; } /* * The following cases all require that EXF_NOBLOB * is not set. */ if (ex->ex_flags & EXF_NOBLOB) continue; /* Case 2. */ if ((start == rp->er_start) && (end < rp->er_end)) { rp->er_start = (end + 1); goto done; } /* Case 3. */ if ((start > rp->er_start) && (end == rp->er_end)) { rp->er_end = (start - 1); goto done; } /* Case 4. */ if ((start > rp->er_start) && (end < rp->er_end)) { struct extent_region *nrp; /* Allocate a region descriptor. */ nrp = extent_alloc_region_descriptor(ex, flags); if (nrp == NULL) return (ENOMEM); /* Fill in new descriptor. */ nrp->er_start = end + 1; nrp->er_end = rp->er_end; /* Adjust current descriptor. */ rp->er_end = start - 1; /* Instert new descriptor after current. */ LIST_INSERT_AFTER(rp, nrp, er_link); goto done; } } /* Region not found, or request otherwise invalid. */ extent_print(ex); kprintf("extent_free: start 0x%lx, end 0x%lx\n", start, end); panic("extent_free: region not found"); done: if (ex->ex_flags & EXF_WANTED) { ex->ex_flags &= ~EXF_WANTED; wakeup(ex); } return (0); } static struct extent_region * extent_alloc_region_descriptor(ex, flags) struct extent *ex; int flags; { struct extent_region *rp; int s; if (ex->ex_flags & EXF_FIXED) { struct extent_fixed *fex = (struct extent_fixed *)ex; while (fex->fex_freelist.lh_first == NULL) { if (flags & EX_MALLOCOK) goto alloc; if ((flags & EX_WAITOK) == 0) return (NULL); ex->ex_flags |= EXF_FLWANTED; if (tsleep(&fex->fex_freelist, PRIBIO | ((flags & EX_CATCH) ? PCATCH : 0), "extnt", 0)) return (NULL); } /* Atomic. */ s = splhigh(); rp = fex->fex_freelist.lh_first; LIST_REMOVE(rp, er_link); splx(s); rp->er_flags = 0; return (rp); } alloc: rp = (struct extent_region *) malloc(sizeof(struct extent_region), ex->ex_mtype, (flags & EX_WAITOK) ? M_WAITOK : M_NOWAIT); rp->er_flags = ER_ALLOC; return (rp); } static void extent_free_region_descriptor(ex, rp) struct extent *ex; struct extent_region *rp; { if ((rp->er_flags & ER_ALLOC) == 0) { struct extent_fixed *fex = (struct extent_fixed *)ex; LIST_INSERT_HEAD(&fex->fex_freelist, rp, er_link); if (ex->ex_flags & EXF_FLWANTED) { ex->ex_flags &= ~EXF_FLWANTED; wakeup(&fex->fex_freelist); } } else free(rp, ex->ex_mtype); } void extent_print(ex) struct extent *ex; { struct extent_region *rp; if (ex == NULL) panic("extent_print: NULL extent"); kprintf("extent `%s' (0x%lx - 0x%lx), flags = 0x%x\n", ex->ex_name, ex->ex_start, ex->ex_end, ex->ex_flags); for (rp = ex->ex_regions.lh_first; rp != NULL; rp = rp->er_link.le_next) kprintf(" 0x%lx - 0x%lx\n", rp->er_start, rp->er_end); }