res_gdt.c revision 1ca1059fd0126fd2c065f272a566c18f14bab16d 
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 Public
9 * License.
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	blk_t			dindir_blk, rsv_off, gdt_off, gdt_blk;
69	int			dindir_dirty = 0, inode_dirty = 0;
70
71	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
72
73	sb = fs->super;
74
75	retval = ext2fs_get_array(2, fs->blocksize, &dindir_buf);
76	if (retval)
77		goto out_free;
78	gdt_buf = (__u32 *)((char *)dindir_buf + fs->blocksize);
79
80	retval = ext2fs_read_inode(fs, EXT2_RESIZE_INO, &inode);
81	if (retval)
82		goto out_free;
83
84	/* Maximum possible file size (we donly use the dindirect blocks) */
85	apb = EXT2_ADDR_PER_BLOCK(sb);
86	if ((dindir_blk = inode.i_block[EXT2_DIND_BLOCK])) {
87#ifdef RES_GDT_DEBUG
88		printf("reading GDT dindir %u\n", dindir_blk);
89#endif
90		retval = ext2fs_read_ind_block(fs, dindir_blk, dindir_buf);
91		if (retval)
92			goto out_inode;
93	} else {
94		blk_t goal = sb->s_first_data_block + fs->desc_blocks +
95			sb->s_reserved_gdt_blocks + 2 +
96			fs->inode_blocks_per_group;
97
98		retval = ext2fs_alloc_block(fs, goal, 0, &dindir_blk);
99		if (retval)
100			goto out_free;
101		inode.i_mode = LINUX_S_IFREG | 0600;
102		inode.i_links_count = 1;
103		inode.i_block[EXT2_DIND_BLOCK] = dindir_blk;
104		ext2fs_iblk_set(fs, &inode, 1);
105		memset(dindir_buf, 0, fs->blocksize);
106#ifdef RES_GDT_DEBUG
107		printf("allocated GDT dindir %u\n", dindir_blk);
108#endif
109		dindir_dirty = inode_dirty = 1;
110		inode_size = apb*apb + apb + EXT2_NDIR_BLOCKS;
111		inode_size *= fs->blocksize;
112		inode.i_size = inode_size & 0xFFFFFFFF;
113		inode.i_size_high = (inode_size >> 32) & 0xFFFFFFFF;
114		if(inode.i_size_high) {
115			sb->s_feature_ro_compat |=
116				EXT2_FEATURE_RO_COMPAT_LARGE_FILE;
117		}
118		inode.i_ctime = fs->now ? fs->now : time(0);
119	}
120
121	for (rsv_off = 0, gdt_off = fs->desc_blocks,
122	     gdt_blk = sb->s_first_data_block + 1 + fs->desc_blocks;
123	     rsv_off < sb->s_reserved_gdt_blocks;
124	     rsv_off++, gdt_off++, gdt_blk++) {
125		unsigned int three = 1, five = 5, seven = 7;
126		unsigned int grp, last = 0;
127		int gdt_dirty = 0;
128
129		gdt_off %= apb;
130		if (!dindir_buf[gdt_off]) {
131			/* FIXME XXX XXX
132			blk_t new_blk;
133
134			retval = ext2fs_new_block(fs, gdt_blk, 0, &new_blk);
135			if (retval)
136				goto out_free;
137			if (new_blk != gdt_blk) {
138				// XXX free block
139				retval = -1; // XXX
140			}
141			*/
142			gdt_dirty = dindir_dirty = inode_dirty = 1;
143			memset(gdt_buf, 0, fs->blocksize);
144			dindir_buf[gdt_off] = gdt_blk;
145			ext2fs_iblk_add_blocks(fs, &inode, 1);
146#ifdef RES_GDT_DEBUG
147			printf("added primary GDT block %u at %u[%u]\n",
148			       gdt_blk, dindir_blk, gdt_off);
149#endif
150		} else if (dindir_buf[gdt_off] == gdt_blk) {
151#ifdef RES_GDT_DEBUG
152			printf("reading primary GDT block %u\n", gdt_blk);
153#endif
154			retval = ext2fs_read_ind_block(fs, gdt_blk, gdt_buf);
155			if (retval)
156				goto out_dindir;
157		} else {
158#ifdef RES_GDT_DEBUG
159			printf("bad primary GDT %u != %u at %u[%u]\n",
160			       dindir_buf[gdt_off], gdt_blk,dindir_blk,gdt_off);
161#endif
162			retval = EXT2_ET_RESIZE_INODE_CORRUPT;
163			goto out_dindir;
164		}
165
166		while ((grp = list_backups(fs, &three, &five, &seven)) <
167		       fs->group_desc_count) {
168			blk_t expect = gdt_blk + grp * sb->s_blocks_per_group;
169
170			if (!gdt_buf[last]) {
171#ifdef RES_GDT_DEBUG
172				printf("added backup GDT %u grp %u@%u[%u]\n",
173				       expect, grp, gdt_blk, last);
174#endif
175				gdt_buf[last] = expect;
176				ext2fs_iblk_add_blocks(fs, &inode, 1);
177				gdt_dirty = inode_dirty = 1;
178			} else if (gdt_buf[last] != expect) {
179#ifdef RES_GDT_DEBUG
180				printf("bad backup GDT %u != %u at %u[%u]\n",
181				       gdt_buf[last], expect, gdt_blk, last);
182#endif
183				retval = EXT2_ET_RESIZE_INODE_CORRUPT;
184				goto out_dindir;
185			}
186			last++;
187		}
188		if (gdt_dirty) {
189#ifdef RES_GDT_DEBUG
190			printf("writing primary GDT block %u\n", gdt_blk);
191#endif
192			retval = ext2fs_write_ind_block(fs, gdt_blk, gdt_buf);
193			if (retval)
194				goto out_dindir;
195		}
196	}
197
198out_dindir:
199	if (dindir_dirty) {
200		retval2 = ext2fs_write_ind_block(fs, dindir_blk, dindir_buf);
201		if (!retval)
202			retval = retval2;
203	}
204out_inode:
205#ifdef RES_GDT_DEBUG
206	printf("inode.i_blocks = %u, i_size = %u\n", inode.i_blocks,
207	       inode.i_size);
208#endif
209	if (inode_dirty) {
210		inode.i_atime = inode.i_mtime = fs->now ? fs->now : time(0);
211		retval2 = ext2fs_write_inode(fs, EXT2_RESIZE_INO, &inode);
212		if (!retval)
213			retval = retval2;
214	}
215out_free:
216	ext2fs_free_mem(&dindir_buf);
217	return retval;
218}
219
220