res_gdt.c revision cf5301d7f2c3bbed3d26600335102414cbf0c4ba 
1/*
2 * res_gdt.c --- reserve blocks for growing the group descriptor table
3 *               during online resizing.
4 *
5 * Copyright (C) 2002 Andreas Dilger
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
10 * %End-Header%
11 */
12
13#include <stdio.h>
14#include <string.h>
15#include <time.h>
16#include "ext2_fs.h"
17#include "ext2fs.h"
18
19/*
20 * Iterate through the groups which hold BACKUP superblock/GDT copies in an
21 * ext3 filesystem.  The counters should be initialized to 1, 5, and 7 before
22 * calling this for the first time.  In a sparse filesystem it will be the
23 * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
24 * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
25 */
26static unsigned int list_backups(ext2_filsys fs, unsigned int *three,
27				 unsigned int *five, unsigned int *seven)
28{
29	unsigned int *min = three;
30	int mult = 3;
31	unsigned int ret;
32
33	if (!(fs->super->s_feature_ro_compat &
34	      EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
35		ret = *min;
36		*min += 1;
37		return ret;
38	}
39
40	if (*five < *min) {
41		min = five;
42		mult = 5;
43	}
44	if (*seven < *min) {
45		min = seven;
46		mult = 7;
47	}
48
49	ret = *min;
50	*min *= mult;
51
52	return ret;
53}
54
55/*
56 * This code assumes that the reserved blocks have already been marked in-use
57 * during ext2fs_initialize(), so that they are not allocated for other
58 * uses before we can add them to the resize inode (which has to come
59 * after the creation of the inode table).
60 */
61errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
62{
63	errcode_t		retval, retval2;
64	struct ext2_super_block	*sb;
65	struct ext2_inode	inode;
66	__u32			*dindir_buf, *gdt_buf;
67	unsigned long long	apb, inode_size;
68	/* FIXME-64 - can't deal with extents */
69	blk_t			dindir_blk, rsv_off, gdt_off, gdt_blk;
70	int			dindir_dirty = 0, inode_dirty = 0;
71
72	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
73
74	sb = fs->super;
75
76	retval = ext2fs_get_array(2, fs->blocksize, &dindir_buf);
77	if (retval)
78		return retval;
79	gdt_buf = (__u32 *)((char *)dindir_buf + fs->blocksize);
80
81	retval = ext2fs_read_inode(fs, EXT2_RESIZE_INO, &inode);
82	if (retval)
83		goto out_free;
84
85	/* Maximum possible file size (we donly use the dindirect blocks) */
86	apb = EXT2_ADDR_PER_BLOCK(sb);
87	if ((dindir_blk = inode.i_block[EXT2_DIND_BLOCK])) {
88#ifdef RES_GDT_DEBUG
89		printf("reading GDT dindir %u\n", dindir_blk);
90#endif
91		retval = ext2fs_read_ind_block(fs, dindir_blk, dindir_buf);
92		if (retval)
93			goto out_inode;
94	} else {
95		blk_t goal = sb->s_first_data_block + fs->desc_blocks +
96			sb->s_reserved_gdt_blocks + 2 +
97			fs->inode_blocks_per_group;
98
99		retval = ext2fs_alloc_block(fs, goal, 0, &dindir_blk);
100		if (retval)
101			goto out_free;
102		inode.i_mode = LINUX_S_IFREG | 0600;
103		inode.i_links_count = 1;
104		inode.i_block[EXT2_DIND_BLOCK] = dindir_blk;
105		ext2fs_iblk_set(fs, &inode, 1);
106		memset(dindir_buf, 0, fs->blocksize);
107#ifdef RES_GDT_DEBUG
108		printf("allocated GDT dindir %u\n", dindir_blk);
109#endif
110		dindir_dirty = inode_dirty = 1;
111		inode_size = apb*apb + apb + EXT2_NDIR_BLOCKS;
112		inode_size *= fs->blocksize;
113		inode.i_size = inode_size & 0xFFFFFFFF;
114		inode.i_size_high = (inode_size >> 32) & 0xFFFFFFFF;
115		if(inode.i_size_high) {
116			sb->s_feature_ro_compat |=
117				EXT2_FEATURE_RO_COMPAT_LARGE_FILE;
118		}
119		inode.i_ctime = fs->now ? fs->now : time(0);
120	}
121
122	for (rsv_off = 0, gdt_off = fs->desc_blocks,
123	     gdt_blk = sb->s_first_data_block + 1 + fs->desc_blocks;
124	     rsv_off < sb->s_reserved_gdt_blocks;
125	     rsv_off++, gdt_off++, gdt_blk++) {
126		unsigned int three = 1, five = 5, seven = 7;
127		unsigned int grp, last = 0;
128		int gdt_dirty = 0;
129
130		gdt_off %= apb;
131		if (!dindir_buf[gdt_off]) {
132			/* FIXME XXX XXX
133			blk_t new_blk;
134
135			retval = ext2fs_new_block(fs, gdt_blk, 0, &new_blk);
136			if (retval)
137				goto out_free;
138			if (new_blk != gdt_blk) {
139				// XXX free block
140				retval = -1; // XXX
141			}
142			*/
143			gdt_dirty = dindir_dirty = inode_dirty = 1;
144			memset(gdt_buf, 0, fs->blocksize);
145			dindir_buf[gdt_off] = gdt_blk;
146			ext2fs_iblk_add_blocks(fs, &inode, 1);
147#ifdef RES_GDT_DEBUG
148			printf("added primary GDT block %u at %u[%u]\n",
149			       gdt_blk, dindir_blk, gdt_off);
150#endif
151		} else if (dindir_buf[gdt_off] == gdt_blk) {
152#ifdef RES_GDT_DEBUG
153			printf("reading primary GDT block %u\n", gdt_blk);
154#endif
155			retval = ext2fs_read_ind_block(fs, gdt_blk, gdt_buf);
156			if (retval)
157				goto out_dindir;
158		} else {
159#ifdef RES_GDT_DEBUG
160			printf("bad primary GDT %u != %u at %u[%u]\n",
161			       dindir_buf[gdt_off], gdt_blk,dindir_blk,gdt_off);
162#endif
163			retval = EXT2_ET_RESIZE_INODE_CORRUPT;
164			goto out_dindir;
165		}
166
167		while ((grp = list_backups(fs, &three, &five, &seven)) <
168		       fs->group_desc_count) {
169			blk_t expect = gdt_blk + grp * sb->s_blocks_per_group;
170
171			if (!gdt_buf[last]) {
172#ifdef RES_GDT_DEBUG
173				printf("added backup GDT %u grp %u@%u[%u]\n",
174				       expect, grp, gdt_blk, last);
175#endif
176				gdt_buf[last] = expect;
177				ext2fs_iblk_add_blocks(fs, &inode, 1);
178				gdt_dirty = inode_dirty = 1;
179			} else if (gdt_buf[last] != expect) {
180#ifdef RES_GDT_DEBUG
181				printf("bad backup GDT %u != %u at %u[%u]\n",
182				       gdt_buf[last], expect, gdt_blk, last);
183#endif
184				retval = EXT2_ET_RESIZE_INODE_CORRUPT;
185				goto out_dindir;
186			}
187			last++;
188		}
189		if (gdt_dirty) {
190#ifdef RES_GDT_DEBUG
191			printf("writing primary GDT block %u\n", gdt_blk);
192#endif
193			retval = ext2fs_write_ind_block(fs, gdt_blk, gdt_buf);
194			if (retval)
195				goto out_dindir;
196		}
197	}
198
199out_dindir:
200	if (dindir_dirty) {
201		retval2 = ext2fs_write_ind_block(fs, dindir_blk, dindir_buf);
202		if (!retval)
203			retval = retval2;
204	}
205out_inode:
206#ifdef RES_GDT_DEBUG
207	printf("inode.i_blocks = %u, i_size = %u\n", inode.i_blocks,
208	       inode.i_size);
209#endif
210	if (inode_dirty) {
211		inode.i_atime = inode.i_mtime = fs->now ? fs->now : time(0);
212		retval2 = ext2fs_write_new_inode(fs, EXT2_RESIZE_INO, &inode);
213		if (!retval)
214			retval = retval2;
215	}
216out_free:
217	ext2fs_free_mem(&dindir_buf);
218	return retval;
219}
220
221