res_gdt.c revision dc8ce3463791366ac844d3f0436709511fa09c49 
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	int			rsv_add;
68	unsigned long long	apb, inode_size;
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	if (!sb->s_reserved_gdt_blocks)
76		return 0;
77
78	retval = ext2fs_get_mem(2 * fs->blocksize, (void **)&dindir_buf);
79	if (retval)
80		goto out_free;
81	gdt_buf = (__u32 *)((char *)dindir_buf + fs->blocksize);
82
83	retval = ext2fs_read_inode(fs, EXT2_RESIZE_INO, &inode);
84	if (retval)
85		goto out_free;
86
87	/* Maximum possible file size (we donly use the dindirect blocks) */
88	apb = EXT2_ADDR_PER_BLOCK(sb);
89	rsv_add = fs->blocksize / 512;
90	if ((dindir_blk = inode.i_block[EXT2_DIND_BLOCK])) {
91#ifdef RES_GDT_DEBUG
92		printf("reading GDT dindir %u\n", dindir_blk);
93#endif
94		retval = ext2fs_read_ind_block(fs, dindir_blk, dindir_buf);
95		if (retval)
96			goto out_inode;
97	} else {
98		blk_t goal = 3 + sb->s_reserved_gdt_blocks +
99			fs->desc_blocks + fs->inode_blocks_per_group;
100
101		retval = ext2fs_alloc_block(fs, goal, 0, &dindir_blk);
102		if (retval)
103			goto out_free;
104		inode.i_mode = LINUX_S_IFREG | 0600;
105		inode.i_links_count = 1;
106		inode.i_block[EXT2_DIND_BLOCK] = dindir_blk;
107		inode.i_blocks = rsv_add;
108		memset(dindir_buf, 0, fs->blocksize);
109#ifdef RES_GDT_DEBUG
110		printf("allocated GDT dindir %u\n", dindir_blk);
111#endif
112		dindir_dirty = inode_dirty = 1;
113		inode_size = apb*apb + apb + EXT2_NDIR_BLOCKS;
114		inode_size *= fs->blocksize;
115		inode.i_size = inode_size & 0xFFFFFFFF;
116		inode.i_size_high = (inode_size >> 32) & 0xFFFFFFFF;
117		if(inode.i_size_high) {
118			sb->s_feature_ro_compat |=
119				EXT2_FEATURE_RO_COMPAT_LARGE_FILE;
120		}
121		inode.i_ctime = time(0);
122	}
123
124	for (rsv_off = 0, gdt_off = fs->desc_blocks,
125	     gdt_blk = sb->s_first_data_block + 1 + fs->desc_blocks;
126	     rsv_off < sb->s_reserved_gdt_blocks;
127	     rsv_off++, gdt_off++, gdt_blk++) {
128		unsigned int three = 1, five = 5, seven = 7;
129		unsigned int grp, last = 0;
130		int gdt_dirty = 0;
131
132		gdt_off %= apb;
133		if (!dindir_buf[gdt_off]) {
134			/* FIXME XXX XXX
135			blk_t new_blk;
136
137			retval = ext2fs_new_block(fs, gdt_blk, 0, &new_blk);
138			if (retval)
139				goto out_free;
140			if (new_blk != gdt_blk) {
141				// XXX free block
142				retval = -1; // XXX
143			}
144			*/
145			gdt_dirty = dindir_dirty = inode_dirty = 1;
146			memset(gdt_buf, 0, fs->blocksize);
147			dindir_buf[gdt_off] = gdt_blk;
148			inode.i_blocks += rsv_add;
149#ifdef RES_GDT_DEBUG
150			printf("added primary GDT block %u at %u[%u]\n",
151			       gdt_blk, dindir_blk, gdt_off);
152#endif
153		} else if (dindir_buf[gdt_off] == gdt_blk) {
154#ifdef RES_GDT_DEBUG
155			printf("reading primary GDT block %u\n", gdt_blk);
156#endif
157			retval = ext2fs_read_ind_block(fs, gdt_blk, gdt_buf);
158			if (retval)
159				goto out_dindir;
160		} else {
161#ifdef RES_GDT_DEBUG
162			printf("bad primary GDT %u != %u at %u[%u]\n",
163			       dindir_buf[gdt_off], gdt_blk,dindir_blk,gdt_off);
164#endif
165			retval = EXT2_ET_RESIZE_INODE_CORRUPT;
166			goto out_dindir;
167		}
168
169		while ((grp = list_backups(fs, &three, &five, &seven)) <
170		       fs->group_desc_count) {
171			blk_t expect = gdt_blk + grp * sb->s_blocks_per_group;
172
173			if (!gdt_buf[last]) {
174#ifdef RES_GDT_DEBUG
175				printf("added backup GDT %u grp %u@%u[%u]\n",
176				       expect, grp, gdt_blk, last);
177#endif
178				gdt_buf[last] = expect;
179				inode.i_blocks += rsv_add;
180				gdt_dirty = inode_dirty = 1;
181			} else if (gdt_buf[last] != expect) {
182#ifdef RES_GDT_DEBUG
183				printf("bad backup GDT %u != %u at %u[%u]\n",
184				       gdt_buf[last], expect, gdt_blk, last);
185#endif
186				retval = EXT2_ET_RESIZE_INODE_CORRUPT;
187				goto out_dindir;
188			}
189			last++;
190		}
191		if (gdt_dirty) {
192#ifdef RES_GDT_DEBUG
193			printf("writing primary GDT block %u\n", gdt_blk);
194#endif
195			retval = ext2fs_write_ind_block(fs, gdt_blk, gdt_buf);
196			if (retval)
197				goto out_dindir;
198		}
199	}
200
201out_dindir:
202	if (dindir_dirty) {
203		retval2 = ext2fs_write_ind_block(fs, dindir_blk, dindir_buf);
204		if (!retval)
205			retval = retval2;
206	}
207out_inode:
208#ifdef RES_GDT_DEBUG
209	printf("inode.i_blocks = %u, i_size = %u\n", inode.i_blocks,
210	       inode.i_size);
211#endif
212	if (inode_dirty) {
213		inode.i_atime = inode.i_mtime = time(0);
214		retval2 = ext2fs_write_inode(fs, EXT2_RESIZE_INO, &inode);
215		if (!retval)
216			retval = retval2;
217	}
218out_free:
219	ext2fs_free_mem((void **)&dindir_buf);
220	return retval;
221}
222
223