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extent-scan.c

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1/* extent-scan.c -- core functions for scanning extents-
2 Copyright (C) 2010-2018 Free Software Foundation, Inc.-
3-
4 This program is free software: you can redistribute it and/or modify-
5 it under the terms of the GNU General Public License as published by-
6 the Free Software Foundation, either version 3 of the License, or-
7 (at your option) any later version.-
8-
9 This program is distributed in the hope that it will be useful,-
10 but WITHOUT ANY WARRANTY; without even the implied warranty of-
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the-
12 GNU General Public License for more details.-
13-
14 You should have received a copy of the GNU General Public License-
15 along with this program. If not, see <https://www.gnu.org/licenses/>.-
16-
17 Written by Jie Liu (jeff.liu@oracle.com). */-
18-
19#include <config.h>-
20#include <sys/types.h>-
21#include <sys/ioctl.h>-
22#include <sys/utsname.h>-
23#include <assert.h>-
24-
25#include "system.h"-
26#include "extent-scan.h"-
27#include "fiemap.h"-
28#include "xstrtol.h"-
29-
30-
31/* Work around Linux kernel issues on BTRFS and EXT4. */-
32static bool-
33extent_need_sync (void)-
34{-
35 /* For now always return true, to be on the safe side.-
36 If/when FIEMAP semantics are well defined (before SEEK_HOLE support-
37 is usable) and kernels implementing them are in use, we may relax-
38 this once again. */-
39 return true;
executed 65 times by 1 test: return 1 ;
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65
40-
41#if FIEMAP_BEHAVIOR_IS_DEFINED_AND_USABLE-
42 static int need_sync = -1;-
43-
44 if (need_sync == -1)-
45 {-
46 struct utsname name;-
47 need_sync = 0; /* No workaround by default. */-
48-
49# ifdef __linux__-
50 if (uname (&name) != -1 && STRNCMP_LIT (name.release, "2.6.") == 0)-
51 {-
52 unsigned long val;-
53 if (xstrtoul (name.release + 4, NULL, 10, &val, NULL) == LONGINT_OK)-
54 {-
55 if (val < 39)-
56 need_sync = 1;-
57 }-
58 }-
59# endif-
60 }-
61-
62 return need_sync;-
63#endif-
64}-
65-
66/* Allocate space for struct extent_scan, initialize the entries if-
67 necessary and return it as the input argument of extent_scan_read(). */-
68extern void-
69extent_scan_init (int src_fd, struct extent_scan *scan)-
70{-
71 scan->fd = src_fd;-
72 scan->ei_count = 0;-
73 scan->ext_info = NULL;-
74 scan->scan_start = 0;-
75 scan->initial_scan_failed = false;-
76 scan->hit_final_extent = false;-
77 scan->fm_flags = extent_need_sync () ? FIEMAP_FLAG_SYNC : 0;
extent_need_sync ()Description
TRUEevaluated 65 times by 1 test
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FALSEnever evaluated
0-65
78}
executed 65 times by 1 test: end of block
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65
79-
80#ifdef __linux__-
81# ifndef FS_IOC_FIEMAP-
82# define FS_IOC_FIEMAP _IOWR ('f', 11, struct fiemap)-
83# endif-
84/* Call ioctl(2) with FS_IOC_FIEMAP (available in linux 2.6.27) to-
85 obtain a map of file extents excluding holes. */-
86extern bool-
87extent_scan_read (struct extent_scan *scan)-
88{-
89 unsigned int si = 0;-
90 struct extent_info *last_ei = scan->ext_info;-
91-
92 while (true)-
93 {-
94 union { struct fiemap f; char c[4096]; } fiemap_buf;-
95 struct fiemap *fiemap = &fiemap_buf.f;-
96 struct fiemap_extent *fm_extents = &fiemap->fm_extents[0];-
97 enum { count = (sizeof fiemap_buf - sizeof *fiemap)/sizeof *fm_extents };-
98 verify (count > 1);-
99-
100 /* This is required at least to initialize fiemap->fm_start,-
101 but also serves (in mid 2010) to appease valgrind, which-
102 appears not to know the semantics of the FIEMAP ioctl. */-
103 memset (&fiemap_buf, 0, sizeof fiemap_buf);-
104-
105 fiemap->fm_start = scan->scan_start;-
106 fiemap->fm_flags = scan->fm_flags;-
107 fiemap->fm_extent_count = count;-
108 fiemap->fm_length = FIEMAP_MAX_OFFSET - scan->scan_start;-
109-
110 /* Fall back to the standard copy if call ioctl(2) failed for-
111 the first time. */-
112 if (ioctl (scan->fd, FS_IOC_FIEMAP, fiemap) < 0)
ioctl (scan->f... , fiemap) < 0Description
TRUEevaluated 5 times by 1 test
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FALSEevaluated 68 times by 1 test
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5-68
113 {-
114 if (scan->scan_start == 0)
scan->scan_start == 0Description
TRUEevaluated 5 times by 1 test
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FALSEnever evaluated
0-5
115 scan->initial_scan_failed = true;
executed 5 times by 1 test: scan->initial_scan_failed = 1 ;
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116 return false;
executed 5 times by 1 test: return 0 ;
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5
117 }-
118-
119 /* If 0 extents are returned, then no more scans are needed. */-
120 if (fiemap->fm_mapped_extents == 0)
fiemap->fm_mapped_extents == 0Description
TRUEevaluated 4 times by 1 test
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FALSEevaluated 64 times by 1 test
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4-64
121 {-
122 scan->hit_final_extent = true;-
123 return scan->scan_start != 0;
executed 4 times by 1 test: return scan->scan_start != 0;
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4
124 }-
125-
126 assert (scan->ei_count <= SIZE_MAX - fiemap->fm_mapped_extents);-
127 scan->ei_count += fiemap->fm_mapped_extents;-
128 {-
129 /* last_ei points into a buffer that may be freed via xnrealloc.-
130 Record its offset and adjust after allocation. */-
131 size_t prev_idx = last_ei - scan->ext_info;-
132 scan->ext_info = xnrealloc (scan->ext_info, scan->ei_count,-
133 sizeof (struct extent_info));-
134 last_ei = scan->ext_info + prev_idx;-
135 }-
136-
137 unsigned int i = 0;-
138 for (i = 0; i < fiemap->fm_mapped_extents; i++)
i < fiemap->fm_mapped_extentsDescription
TRUEevaluated 1397 times by 1 test
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FALSEevaluated 64 times by 1 test
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64-1397
139 {-
140 assert (fm_extents[i].fe_logical-
141 <= OFF_T_MAX - fm_extents[i].fe_length);-
142-
143 verify (sizeof last_ei->ext_flags >= sizeof fm_extents->fe_flags);-
144-
145 if (si && last_ei->ext_flags
siDescription
TRUEevaluated 1333 times by 1 test
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FALSEevaluated 64 times by 1 test
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last_ei->ext_f...& ~0x00000001)Description
TRUEevaluated 1330 times by 1 test
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FALSEevaluated 3 times by 1 test
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3-1333
146 == (fm_extents[i].fe_flags & ~FIEMAP_EXTENT_LAST)
last_ei->ext_f...& ~0x00000001)Description
TRUEevaluated 1330 times by 1 test
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FALSEevaluated 3 times by 1 test
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3-1330
147 && (last_ei->ext_logical + last_ei->ext_length
(last_ei->ext_...i].fe_logical)Description
TRUEevaluated 3 times by 1 test
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FALSEevaluated 1327 times by 1 test
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3-1327
148 == fm_extents[i].fe_logical))
(last_ei->ext_...i].fe_logical)Description
TRUEevaluated 3 times by 1 test
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3-1327
149 {-
150 /* Merge previous with last. */-
151 last_ei->ext_length += fm_extents[i].fe_length;-
152 /* Copy flags in case different. */-
153 last_ei->ext_flags = fm_extents[i].fe_flags;-
154 }
executed 3 times by 1 test: end of block
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3
155 else if ((si == 0 && scan->scan_start > fm_extents[i].fe_logical)
si == 0Description
TRUEevaluated 64 times by 1 test
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FALSEevaluated 1330 times by 1 test
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scan->scan_sta...[i].fe_logicalDescription
TRUEnever evaluated
FALSEevaluated 64 times by 1 test
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0-1330
156 || (si && (last_ei->ext_logical + last_ei->ext_length
siDescription
TRUEevaluated 1330 times by 1 test
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FALSEevaluated 64 times by 1 test
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(last_ei->ext_...i].fe_logical)Description
TRUEnever evaluated
FALSEevaluated 1330 times by 1 test
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0-1330
157 > fm_extents[i].fe_logical)))
(last_ei->ext_...i].fe_logical)Description
TRUEnever evaluated
FALSEevaluated 1330 times by 1 test
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0-1330
158 {-
159 /* BTRFS before 2.6.38 could return overlapping extents-
160 for sparse files. We adjust the returned extents-
161 rather than failing, as otherwise it would be inefficient-
162 to detect this on the initial scan. */-
163 uint64_t new_logical;-
164 uint64_t length_adjust;-
165 if (si == 0)
si == 0Description
TRUEnever evaluated
FALSEnever evaluated
0
166 new_logical = scan->scan_start;
never executed: new_logical = scan->scan_start;
0
167 else-
168 {-
169 /* We could return here if scan->scan_start == 0-
170 but don't so as to minimize special cases. */-
171 new_logical = last_ei->ext_logical + last_ei->ext_length;-
172 }
never executed: end of block
0
173 length_adjust = new_logical - fm_extents[i].fe_logical;-
174 /* If an extent is contained within the previous one, fail. */-
175 if (length_adjust < fm_extents[i].fe_length)
length_adjust ...s[i].fe_lengthDescription
TRUEnever evaluated
FALSEnever evaluated
0
176 {-
177 if (scan->scan_start == 0)
scan->scan_start == 0Description
TRUEnever evaluated
FALSEnever evaluated
0
178 scan->initial_scan_failed = true;
never executed: scan->initial_scan_failed = 1 ;
0
179 return false;
never executed: return 0 ;
0
180 }-
181 fm_extents[i].fe_logical = new_logical;-
182 fm_extents[i].fe_length -= length_adjust;-
183 /* Process the adjusted extent again. */-
184 i--;-
185 continue;
never executed: continue;
0
186 }-
187 else-
188 {-
189 last_ei = scan->ext_info + si;-
190 last_ei->ext_logical = fm_extents[i].fe_logical;-
191 last_ei->ext_length = fm_extents[i].fe_length;-
192 last_ei->ext_flags = fm_extents[i].fe_flags;-
193 si++;-
194 }
executed 1394 times by 1 test: end of block
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1394
195 }-
196-
197 if (last_ei->ext_flags & FIEMAP_EXTENT_LAST)
last_ei->ext_f...s & 0x00000001Description
TRUEevaluated 56 times by 1 test
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FALSEevaluated 8 times by 1 test
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8-56
198 scan->hit_final_extent = true;
executed 56 times by 1 test: scan->hit_final_extent = 1 ;
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56
199-
200 /* If we have enough extents, discard the last as it might-
201 be merged with one from the next scan. */-
202 if (si > count && !scan->hit_final_extent)
si > countDescription
TRUEnever evaluated
FALSEevaluated 64 times by 1 test
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!scan->hit_final_extentDescription
TRUEnever evaluated
FALSEnever evaluated
0-64
203 last_ei = scan->ext_info + --si - 1;
never executed: last_ei = scan->ext_info + --si - 1;
0
204-
205 /* We don't bother reallocating any trailing slots. */-
206 scan->ei_count = si;-
207-
208 if (scan->hit_final_extent)
scan->hit_final_extentDescription
TRUEevaluated 56 times by 1 test
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FALSEevaluated 8 times by 1 test
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209 break;
executed 56 times by 1 test: break;
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56
210 else-
211 scan->scan_start = last_ei->ext_logical + last_ei->ext_length;
executed 8 times by 1 test: scan->scan_start = last_ei->ext_logical + last_ei->ext_length;
Executed by:
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8
212-
213 if (si >= count)
si >= countDescription
TRUEevaluated 8 times by 1 test
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FALSEnever evaluated
0-8
214 break;
executed 8 times by 1 test: break;
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8
215 }
never executed: end of block
0
216-
217 return true;
executed 64 times by 1 test: return 1 ;
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64
218}-
219#else-
220extern bool-
221extent_scan_read (struct extent_scan *scan _GL_UNUSED)-
222{-
223 scan->initial_scan_failed = true;-
224 errno = ENOTSUP;-
225 return false;-
226}-
227#endif-
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