Root/fs/udf/truncate.c

1/*
2 * truncate.c
3 *
4 * PURPOSE
5 * Truncate handling routines for the OSTA-UDF(tm) filesystem.
6 *
7 * COPYRIGHT
8 * This file is distributed under the terms of the GNU General Public
9 * License (GPL). Copies of the GPL can be obtained from:
10 * ftp://prep.ai.mit.edu/pub/gnu/GPL
11 * Each contributing author retains all rights to their own work.
12 *
13 * (C) 1999-2004 Ben Fennema
14 * (C) 1999 Stelias Computing Inc
15 *
16 * HISTORY
17 *
18 * 02/24/99 blf Created.
19 *
20 */
21
22#include "udfdecl.h"
23#include <linux/fs.h>
24#include <linux/mm.h>
25#include <linux/buffer_head.h>
26
27#include "udf_i.h"
28#include "udf_sb.h"
29
30static void extent_trunc(struct inode *inode, struct extent_position *epos,
31             struct kernel_lb_addr *eloc, int8_t etype, uint32_t elen,
32             uint32_t nelen)
33{
34    struct kernel_lb_addr neloc = {};
35    int last_block = (elen + inode->i_sb->s_blocksize - 1) >>
36        inode->i_sb->s_blocksize_bits;
37    int first_block = (nelen + inode->i_sb->s_blocksize - 1) >>
38        inode->i_sb->s_blocksize_bits;
39
40    if (nelen) {
41        if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
42            udf_free_blocks(inode->i_sb, inode, eloc, 0,
43                    last_block);
44            etype = (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30);
45        } else
46            neloc = *eloc;
47        nelen = (etype << 30) | nelen;
48    }
49
50    if (elen != nelen) {
51        udf_write_aext(inode, epos, &neloc, nelen, 0);
52        if (last_block - first_block > 0) {
53            if (etype == (EXT_RECORDED_ALLOCATED >> 30))
54                mark_inode_dirty(inode);
55
56            if (etype != (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
57                udf_free_blocks(inode->i_sb, inode, eloc,
58                        first_block,
59                        last_block - first_block);
60        }
61    }
62}
63
64/*
65 * Truncate the last extent to match i_size. This function assumes
66 * that preallocation extent is already truncated.
67 */
68void udf_truncate_tail_extent(struct inode *inode)
69{
70    struct extent_position epos = {};
71    struct kernel_lb_addr eloc;
72    uint32_t elen, nelen;
73    uint64_t lbcount = 0;
74    int8_t etype = -1, netype;
75    int adsize;
76    struct udf_inode_info *iinfo = UDF_I(inode);
77
78    if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB ||
79        inode->i_size == iinfo->i_lenExtents)
80        return;
81    /* Are we going to delete the file anyway? */
82    if (inode->i_nlink == 0)
83        return;
84
85    if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
86        adsize = sizeof(struct short_ad);
87    else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
88        adsize = sizeof(struct long_ad);
89    else
90        BUG();
91
92    /* Find the last extent in the file */
93    while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
94        etype = netype;
95        lbcount += elen;
96        if (lbcount > inode->i_size) {
97            if (lbcount - inode->i_size >= inode->i_sb->s_blocksize)
98                printk(KERN_WARNING
99                       "udf_truncate_tail_extent(): Too long "
100                       "extent after EOF in inode %u: i_size: "
101                       "%Ld lbcount: %Ld extent %u+%u\n",
102                       (unsigned)inode->i_ino,
103                       (long long)inode->i_size,
104                       (long long)lbcount,
105                       (unsigned)eloc.logicalBlockNum,
106                       (unsigned)elen);
107            nelen = elen - (lbcount - inode->i_size);
108            epos.offset -= adsize;
109            extent_trunc(inode, &epos, &eloc, etype, elen, nelen);
110            epos.offset += adsize;
111            if (udf_next_aext(inode, &epos, &eloc, &elen, 1) != -1)
112                printk(KERN_ERR "udf_truncate_tail_extent(): "
113                       "Extent after EOF in inode %u.\n",
114                       (unsigned)inode->i_ino);
115            break;
116        }
117    }
118    /* This inode entry is in-memory only and thus we don't have to mark
119     * the inode dirty */
120    iinfo->i_lenExtents = inode->i_size;
121    brelse(epos.bh);
122}
123
124void udf_discard_prealloc(struct inode *inode)
125{
126    struct extent_position epos = { NULL, 0, {0, 0} };
127    struct kernel_lb_addr eloc;
128    uint32_t elen;
129    uint64_t lbcount = 0;
130    int8_t etype = -1, netype;
131    int adsize;
132    struct udf_inode_info *iinfo = UDF_I(inode);
133
134    if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB ||
135        inode->i_size == iinfo->i_lenExtents)
136        return;
137
138    if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
139        adsize = sizeof(struct short_ad);
140    else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
141        adsize = sizeof(struct long_ad);
142    else
143        adsize = 0;
144
145    epos.block = iinfo->i_location;
146
147    /* Find the last extent in the file */
148    while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
149        etype = netype;
150        lbcount += elen;
151    }
152    if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
153        epos.offset -= adsize;
154        lbcount -= elen;
155        extent_trunc(inode, &epos, &eloc, etype, elen, 0);
156        if (!epos.bh) {
157            iinfo->i_lenAlloc =
158                epos.offset -
159                udf_file_entry_alloc_offset(inode);
160            mark_inode_dirty(inode);
161        } else {
162            struct allocExtDesc *aed =
163                (struct allocExtDesc *)(epos.bh->b_data);
164            aed->lengthAllocDescs =
165                cpu_to_le32(epos.offset -
166                        sizeof(struct allocExtDesc));
167            if (!UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_STRICT) ||
168                UDF_SB(inode->i_sb)->s_udfrev >= 0x0201)
169                udf_update_tag(epos.bh->b_data, epos.offset);
170            else
171                udf_update_tag(epos.bh->b_data,
172                           sizeof(struct allocExtDesc));
173            mark_buffer_dirty_inode(epos.bh, inode);
174        }
175    }
176    /* This inode entry is in-memory only and thus we don't have to mark
177     * the inode dirty */
178    iinfo->i_lenExtents = lbcount;
179    brelse(epos.bh);
180}
181
182static void udf_update_alloc_ext_desc(struct inode *inode,
183                      struct extent_position *epos,
184                      u32 lenalloc)
185{
186    struct super_block *sb = inode->i_sb;
187    struct udf_sb_info *sbi = UDF_SB(sb);
188
189    struct allocExtDesc *aed = (struct allocExtDesc *) (epos->bh->b_data);
190    int len = sizeof(struct allocExtDesc);
191
192    aed->lengthAllocDescs = cpu_to_le32(lenalloc);
193    if (!UDF_QUERY_FLAG(sb, UDF_FLAG_STRICT) || sbi->s_udfrev >= 0x0201)
194        len += lenalloc;
195
196    udf_update_tag(epos->bh->b_data, len);
197    mark_buffer_dirty_inode(epos->bh, inode);
198}
199
200/*
201 * Truncate extents of inode to inode->i_size. This function can be used only
202 * for making file shorter. For making file longer, udf_extend_file() has to
203 * be used.
204 */
205void udf_truncate_extents(struct inode *inode)
206{
207    struct extent_position epos;
208    struct kernel_lb_addr eloc, neloc = {};
209    uint32_t elen, nelen = 0, indirect_ext_len = 0, lenalloc;
210    int8_t etype;
211    struct super_block *sb = inode->i_sb;
212    sector_t first_block = inode->i_size >> sb->s_blocksize_bits, offset;
213    loff_t byte_offset;
214    int adsize;
215    struct udf_inode_info *iinfo = UDF_I(inode);
216
217    if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
218        adsize = sizeof(struct short_ad);
219    else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
220        adsize = sizeof(struct long_ad);
221    else
222        BUG();
223
224    etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
225    byte_offset = (offset << sb->s_blocksize_bits) +
226        (inode->i_size & (sb->s_blocksize - 1));
227    if (etype == -1) {
228        /* We should extend the file? */
229        WARN_ON(byte_offset);
230        return;
231    }
232    epos.offset -= adsize;
233    extent_trunc(inode, &epos, &eloc, etype, elen, byte_offset);
234    epos.offset += adsize;
235    if (byte_offset)
236        lenalloc = epos.offset;
237    else
238        lenalloc = epos.offset - adsize;
239
240    if (!epos.bh)
241        lenalloc -= udf_file_entry_alloc_offset(inode);
242    else
243        lenalloc -= sizeof(struct allocExtDesc);
244
245    while ((etype = udf_current_aext(inode, &epos, &eloc,
246                     &elen, 0)) != -1) {
247        if (etype == (EXT_NEXT_EXTENT_ALLOCDECS >> 30)) {
248            udf_write_aext(inode, &epos, &neloc, nelen, 0);
249            if (indirect_ext_len) {
250                /* We managed to free all extents in the
251                 * indirect extent - free it too */
252                BUG_ON(!epos.bh);
253                udf_free_blocks(sb, inode, &epos.block,
254                        0, indirect_ext_len);
255            } else if (!epos.bh) {
256                iinfo->i_lenAlloc = lenalloc;
257                mark_inode_dirty(inode);
258            } else
259                udf_update_alloc_ext_desc(inode,
260                        &epos, lenalloc);
261            brelse(epos.bh);
262            epos.offset = sizeof(struct allocExtDesc);
263            epos.block = eloc;
264            epos.bh = udf_tread(sb,
265                    udf_get_lb_pblock(sb, &eloc, 0));
266            if (elen)
267                indirect_ext_len =
268                    (elen + sb->s_blocksize - 1) >>
269                    sb->s_blocksize_bits;
270            else
271                indirect_ext_len = 1;
272        } else {
273            extent_trunc(inode, &epos, &eloc, etype, elen, 0);
274            epos.offset += adsize;
275        }
276    }
277
278    if (indirect_ext_len) {
279        BUG_ON(!epos.bh);
280        udf_free_blocks(sb, inode, &epos.block, 0, indirect_ext_len);
281    } else if (!epos.bh) {
282        iinfo->i_lenAlloc = lenalloc;
283        mark_inode_dirty(inode);
284    } else
285        udf_update_alloc_ext_desc(inode, &epos, lenalloc);
286    iinfo->i_lenExtents = inode->i_size;
287
288    brelse(epos.bh);
289}
290

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