From d1e063beb43e595680c65e3804d1f8ddff53373b Mon Sep 17 00:00:00 2001 From: Guido Guenther Date: Sat, 18 Nov 2006 23:48:07 +0100 Subject: Imported Debian version 0.3.8.8 --- e2fslib/icount.c | 482 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 482 insertions(+) create mode 100644 e2fslib/icount.c (limited to 'e2fslib/icount.c') diff --git a/e2fslib/icount.c b/e2fslib/icount.c new file mode 100644 index 0000000..1ad3940 --- /dev/null +++ b/e2fslib/icount.c @@ -0,0 +1,482 @@ +/* + * icount.c --- an efficient inode count abstraction + * + * Copyright (C) 1997 Theodore Ts'o. + * + * %Begin-Header% + * This file may be redistributed under the terms of the GNU Public + * License. + * %End-Header% + */ + +#if HAVE_UNISTD_H +#include +#endif +#include +#include + +#include "ext2_fs.h" +#include "ext2fs.h" + +/* + * The data storage strategy used by icount relies on the observation + * that most inode counts are either zero (for non-allocated inodes), + * one (for most files), and only a few that are two or more + * (directories and files that are linked to more than one directory). + * + * Also, e2fsck tends to load the icount data sequentially. + * + * So, we use an inode bitmap to indicate which inodes have a count of + * one, and then use a sorted list to store the counts for inodes + * which are greater than one. + * + * We also use an optional bitmap to indicate which inodes are already + * in the sorted list, to speed up the use of this abstraction by + * e2fsck's pass 2. Pass 2 increments inode counts as it finds them, + * so this extra bitmap avoids searching the sorted list to see if a + * particular inode is on the sorted list already. + */ + +struct ext2_icount_el { + ext2_ino_t ino; + __u16 count; +}; + +struct ext2_icount { + errcode_t magic; + ext2fs_inode_bitmap single; + ext2fs_inode_bitmap multiple; + ext2_ino_t count; + ext2_ino_t size; + ext2_ino_t num_inodes; + int cursor; + struct ext2_icount_el *list; +}; + +void ext2fs_free_icount(ext2_icount_t icount) +{ + if (!icount) + return; + + icount->magic = 0; + if (icount->list) + ext2fs_free_mem((void **) &icount->list); + if (icount->single) + ext2fs_free_inode_bitmap(icount->single); + if (icount->multiple) + ext2fs_free_inode_bitmap(icount->multiple); + ext2fs_free_mem((void **) &icount); +} + +errcode_t ext2fs_create_icount2(ext2_filsys fs, int flags, int size, + ext2_icount_t hint, ext2_icount_t *ret) +{ + ext2_icount_t icount; + errcode_t retval; + size_t bytes; + int i; + + if (hint) { + EXT2_CHECK_MAGIC(hint, EXT2_ET_MAGIC_ICOUNT); + if (hint->size > size) + size = (size_t) hint->size; + } + + retval = ext2fs_get_mem(sizeof(struct ext2_icount), (void **) &icount); + if (retval) + return retval; + memset(icount, 0, sizeof(struct ext2_icount)); + + retval = ext2fs_allocate_inode_bitmap(fs, 0, + &icount->single); + if (retval) + goto errout; + + if (flags & EXT2_ICOUNT_OPT_INCREMENT) { + retval = ext2fs_allocate_inode_bitmap(fs, 0, + &icount->multiple); + if (retval) + goto errout; + } else + icount->multiple = 0; + + if (size) { + icount->size = size; + } else { + /* + * Figure out how many special case inode counts we will + * have. We know we will need one for each directory; + * we also need to reserve some extra room for file links + */ + retval = ext2fs_get_num_dirs(fs, &icount->size); + if (retval) + goto errout; + icount->size += fs->super->s_inodes_count / 50; + } + + bytes = (size_t) (icount->size * sizeof(struct ext2_icount_el)); +#if 0 + printf("Icount allocated %d entries, %d bytes.\n", + icount->size, bytes); +#endif + retval = ext2fs_get_mem(bytes, (void **) &icount->list); + if (retval) + goto errout; + memset(icount->list, 0, bytes); + + icount->magic = EXT2_ET_MAGIC_ICOUNT; + icount->count = 0; + icount->cursor = 0; + icount->num_inodes = fs->super->s_inodes_count; + + /* + * Populate the sorted list with those entries which were + * found in the hint icount (since those are ones which will + * likely need to be in the sorted list this time around). + */ + if (hint) { + for (i=0; i < hint->count; i++) + icount->list[i].ino = hint->list[i].ino; + icount->count = hint->count; + } + + *ret = icount; + return 0; + +errout: + ext2fs_free_icount(icount); + return(retval); +} + +errcode_t ext2fs_create_icount(ext2_filsys fs, int flags, int size, + ext2_icount_t *ret) +{ + return ext2fs_create_icount2(fs, flags, size, 0, ret); +} + +/* + * insert_icount_el() --- Insert a new entry into the sorted list at a + * specified position. + */ +static struct ext2_icount_el *insert_icount_el(ext2_icount_t icount, + ext2_ino_t ino, int pos) +{ + struct ext2_icount_el *el; + errcode_t retval; + ext2_ino_t new_size = 0; + int num; + + if (icount->count >= icount->size) { + if (icount->count) { + new_size = icount->list[(unsigned)icount->count-1].ino; + new_size = (ext2_ino_t) (icount->count * + ((float) icount->num_inodes / new_size)); + } + if (new_size < (icount->size + 100)) + new_size = icount->size + 100; +#if 0 + printf("Reallocating icount %d entries...\n", new_size); +#endif + retval = ext2fs_resize_mem((size_t) icount->size * + sizeof(struct ext2_icount_el), + (size_t) new_size * + sizeof(struct ext2_icount_el), + (void **) &icount->list); + if (retval) + return 0; + icount->size = new_size; + } + num = (int) icount->count - pos; + if (num < 0) + return 0; /* should never happen */ + if (num) { + memmove(&icount->list[pos+1], &icount->list[pos], + sizeof(struct ext2_icount_el) * num); + } + icount->count++; + el = &icount->list[pos]; + el->count = 0; + el->ino = ino; + return el; +} + +/* + * get_icount_el() --- given an inode number, try to find icount + * information in the sorted list. If the create flag is set, + * and we can't find an entry, create one in the sorted list. + */ +static struct ext2_icount_el *get_icount_el(ext2_icount_t icount, + ext2_ino_t ino, int create) +{ + float range; + int low, high, mid; + ext2_ino_t lowval, highval; + + if (!icount || !icount->list) + return 0; + + if (create && ((icount->count == 0) || + (ino > icount->list[(unsigned)icount->count-1].ino))) { + return insert_icount_el(icount, ino, (unsigned) icount->count); + } + if (icount->count == 0) + return 0; + + if (icount->cursor >= icount->count) + icount->cursor = 0; + if (ino == icount->list[icount->cursor].ino) + return &icount->list[icount->cursor++]; +#if 0 + printf("Non-cursor get_icount_el: %u\n", ino); +#endif + low = 0; + high = (int) icount->count-1; + while (low <= high) { +#if 0 + mid = (low+high)/2; +#else + if (low == high) + mid = low; + else { + /* Interpolate for efficiency */ + lowval = icount->list[low].ino; + highval = icount->list[high].ino; + + if (ino < lowval) + range = 0; + else if (ino > highval) + range = 1; + else + range = ((float) (ino - lowval)) / + (highval - lowval); + mid = low + ((int) (range * (high-low))); + } +#endif + if (ino == icount->list[mid].ino) { + icount->cursor = mid+1; + return &icount->list[mid]; + } + if (ino < icount->list[mid].ino) + high = mid-1; + else + low = mid+1; + } + /* + * If we need to create a new entry, it should be right at + * low (where high will be left at low-1). + */ + if (create) + return insert_icount_el(icount, ino, low); + return 0; +} + +errcode_t ext2fs_icount_validate(ext2_icount_t icount, FILE *out) +{ + errcode_t ret = 0; + int i; + const char *bad = "bad icount"; + + EXT2_CHECK_MAGIC(icount, EXT2_ET_MAGIC_ICOUNT); + + if (icount->count > icount->size) { + fprintf(out, "%s: count > size\n", bad); + return EXT2_ET_INVALID_ARGUMENT; + } + for (i=1; i < icount->count; i++) { + if (icount->list[i-1].ino >= icount->list[i].ino) { + fprintf(out, "%s: list[%d].ino=%u, list[%d].ino=%u\n", + bad, i-1, icount->list[i-1].ino, + i, icount->list[i].ino); + ret = EXT2_ET_INVALID_ARGUMENT; + } + } + return ret; +} + +errcode_t ext2fs_icount_fetch(ext2_icount_t icount, ext2_ino_t ino, __u16 *ret) +{ + struct ext2_icount_el *el; + + EXT2_CHECK_MAGIC(icount, EXT2_ET_MAGIC_ICOUNT); + + if (!ino || (ino > icount->num_inodes)) + return EXT2_ET_INVALID_ARGUMENT; + + if (ext2fs_test_inode_bitmap(icount->single, ino)) { + *ret = 1; + return 0; + } + if (icount->multiple && + !ext2fs_test_inode_bitmap(icount->multiple, ino)) { + *ret = 0; + return 0; + } + el = get_icount_el(icount, ino, 0); + if (!el) { + *ret = 0; + return 0; + } + *ret = el->count; + return 0; +} + +errcode_t ext2fs_icount_increment(ext2_icount_t icount, ext2_ino_t ino, + __u16 *ret) +{ + struct ext2_icount_el *el; + + EXT2_CHECK_MAGIC(icount, EXT2_ET_MAGIC_ICOUNT); + + if (!ino || (ino > icount->num_inodes)) + return EXT2_ET_INVALID_ARGUMENT; + + if (ext2fs_test_inode_bitmap(icount->single, ino)) { + /* + * If the existing count is 1, then we know there is + * no entry in the list. + */ + el = get_icount_el(icount, ino, 1); + if (!el) + return EXT2_ET_NO_MEMORY; + ext2fs_unmark_inode_bitmap(icount->single, ino); + el->count = 2; + } else if (icount->multiple) { + /* + * The count is either zero or greater than 1; if the + * inode is set in icount->multiple, then there should + * be an entry in the list, so find it using + * get_icount_el(). + */ + if (ext2fs_test_inode_bitmap(icount->multiple, ino)) { + el = get_icount_el(icount, ino, 1); + if (!el) + return EXT2_ET_NO_MEMORY; + el->count++; + } else { + /* + * The count was zero; mark the single bitmap + * and return. + */ + zero_count: + ext2fs_mark_inode_bitmap(icount->single, ino); + if (ret) + *ret = 1; + return 0; + } + } else { + /* + * The count is either zero or greater than 1; try to + * find an entry in the list to determine which. + */ + el = get_icount_el(icount, ino, 0); + if (!el) { + /* No entry means the count was zero */ + goto zero_count; + } + el = get_icount_el(icount, ino, 1); + if (!el) + return EXT2_ET_NO_MEMORY; + el->count++; + } + if (icount->multiple) + ext2fs_mark_inode_bitmap(icount->multiple, ino); + if (ret) + *ret = el->count; + return 0; +} + +errcode_t ext2fs_icount_decrement(ext2_icount_t icount, ext2_ino_t ino, + __u16 *ret) +{ + struct ext2_icount_el *el; + + if (!ino || (ino > icount->num_inodes)) + return EXT2_ET_INVALID_ARGUMENT; + + EXT2_CHECK_MAGIC(icount, EXT2_ET_MAGIC_ICOUNT); + + if (ext2fs_test_inode_bitmap(icount->single, ino)) { + ext2fs_unmark_inode_bitmap(icount->single, ino); + if (icount->multiple) + ext2fs_unmark_inode_bitmap(icount->multiple, ino); + else { + el = get_icount_el(icount, ino, 0); + if (el) + el->count = 0; + } + if (ret) + *ret = 0; + return 0; + } + + if (icount->multiple && + !ext2fs_test_inode_bitmap(icount->multiple, ino)) + return EXT2_ET_INVALID_ARGUMENT; + + el = get_icount_el(icount, ino, 0); + if (!el || el->count == 0) + return EXT2_ET_INVALID_ARGUMENT; + + el->count--; + if (el->count == 1) + ext2fs_mark_inode_bitmap(icount->single, ino); + if ((el->count == 0) && icount->multiple) + ext2fs_unmark_inode_bitmap(icount->multiple, ino); + + if (ret) + *ret = el->count; + return 0; +} + +errcode_t ext2fs_icount_store(ext2_icount_t icount, ext2_ino_t ino, + __u16 count) +{ + struct ext2_icount_el *el; + + if (!ino || (ino > icount->num_inodes)) + return EXT2_ET_INVALID_ARGUMENT; + + EXT2_CHECK_MAGIC(icount, EXT2_ET_MAGIC_ICOUNT); + + if (count == 1) { + ext2fs_mark_inode_bitmap(icount->single, ino); + if (icount->multiple) + ext2fs_unmark_inode_bitmap(icount->multiple, ino); + return 0; + } + if (count == 0) { + ext2fs_unmark_inode_bitmap(icount->single, ino); + if (icount->multiple) { + /* + * If the icount->multiple bitmap is enabled, + * we can just clear both bitmaps and we're done + */ + ext2fs_unmark_inode_bitmap(icount->multiple, ino); + } else { + el = get_icount_el(icount, ino, 0); + if (el) + el->count = 0; + } + return 0; + } + + /* + * Get the icount element + */ + el = get_icount_el(icount, ino, 1); + if (!el) + return EXT2_ET_NO_MEMORY; + el->count = count; + ext2fs_unmark_inode_bitmap(icount->single, ino); + if (icount->multiple) + ext2fs_mark_inode_bitmap(icount->multiple, ino); + return 0; +} + +ext2_ino_t ext2fs_get_icount_size(ext2_icount_t icount) +{ + if (!icount || icount->magic != EXT2_ET_MAGIC_ICOUNT) + return 0; + + return icount->size; +} -- cgit v1.2.3