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1.1 root 1: /*
2: * QEMU Enhanced Disk Format
3: *
4: * Copyright IBM, Corp. 2010
5: *
6: * Authors:
7: * Stefan Hajnoczi <[email protected]>
8: * Anthony Liguori <[email protected]>
9: *
10: * This work is licensed under the terms of the GNU LGPL, version 2 or later.
11: * See the COPYING.LIB file in the top-level directory.
12: *
13: */
14:
15: #ifndef BLOCK_QED_H
16: #define BLOCK_QED_H
17:
18: #include "block_int.h"
19:
20: /* The layout of a QED file is as follows:
21: *
22: * +--------+----------+----------+----------+-----+
23: * | header | L1 table | cluster0 | cluster1 | ... |
24: * +--------+----------+----------+----------+-----+
25: *
26: * There is a 2-level pagetable for cluster allocation:
27: *
28: * +----------+
29: * | L1 table |
30: * +----------+
31: * ,------' | '------.
32: * +----------+ | +----------+
33: * | L2 table | ... | L2 table |
34: * +----------+ +----------+
35: * ,------' | '------.
36: * +----------+ | +----------+
37: * | Data | ... | Data |
38: * +----------+ +----------+
39: *
40: * The L1 table is fixed size and always present. L2 tables are allocated on
41: * demand. The L1 table size determines the maximum possible image size; it
42: * can be influenced using the cluster_size and table_size values.
43: *
44: * All fields are little-endian on disk.
45: */
46:
47: enum {
48: QED_MAGIC = 'Q' | 'E' << 8 | 'D' << 16 | '\0' << 24,
49:
50: /* The image supports a backing file */
51: QED_F_BACKING_FILE = 0x01,
52:
53: /* The image needs a consistency check before use */
54: QED_F_NEED_CHECK = 0x02,
55:
56: /* The backing file format must not be probed, treat as raw image */
57: QED_F_BACKING_FORMAT_NO_PROBE = 0x04,
58:
59: /* Feature bits must be used when the on-disk format changes */
60: QED_FEATURE_MASK = QED_F_BACKING_FILE | /* supported feature bits */
61: QED_F_NEED_CHECK |
62: QED_F_BACKING_FORMAT_NO_PROBE,
63: QED_COMPAT_FEATURE_MASK = 0, /* supported compat feature bits */
64: QED_AUTOCLEAR_FEATURE_MASK = 0, /* supported autoclear feature bits */
65:
66: /* Data is stored in groups of sectors called clusters. Cluster size must
67: * be large to avoid keeping too much metadata. I/O requests that have
68: * sub-cluster size will require read-modify-write.
69: */
70: QED_MIN_CLUSTER_SIZE = 4 * 1024, /* in bytes */
71: QED_MAX_CLUSTER_SIZE = 64 * 1024 * 1024,
72: QED_DEFAULT_CLUSTER_SIZE = 64 * 1024,
73:
74: /* Allocated clusters are tracked using a 2-level pagetable. Table size is
75: * a multiple of clusters so large maximum image sizes can be supported
76: * without jacking up the cluster size too much.
77: */
78: QED_MIN_TABLE_SIZE = 1, /* in clusters */
79: QED_MAX_TABLE_SIZE = 16,
80: QED_DEFAULT_TABLE_SIZE = 4,
1.1.1.3 ! root 81:
! 82: /* Delay to flush and clean image after last allocating write completes */
! 83: QED_NEED_CHECK_TIMEOUT = 5, /* in seconds */
1.1 root 84: };
85:
86: typedef struct {
87: uint32_t magic; /* QED\0 */
88:
89: uint32_t cluster_size; /* in bytes */
90: uint32_t table_size; /* for L1 and L2 tables, in clusters */
91: uint32_t header_size; /* in clusters */
92:
93: uint64_t features; /* format feature bits */
94: uint64_t compat_features; /* compatible feature bits */
95: uint64_t autoclear_features; /* self-resetting feature bits */
96:
97: uint64_t l1_table_offset; /* in bytes */
98: uint64_t image_size; /* total logical image size, in bytes */
99:
100: /* if (features & QED_F_BACKING_FILE) */
101: uint32_t backing_filename_offset; /* in bytes from start of header */
102: uint32_t backing_filename_size; /* in bytes */
103: } QEDHeader;
104:
105: typedef struct {
106: uint64_t offsets[0]; /* in bytes */
107: } QEDTable;
108:
109: /* The L2 cache is a simple write-through cache for L2 structures */
110: typedef struct CachedL2Table {
111: QEDTable *table;
112: uint64_t offset; /* offset=0 indicates an invalidate entry */
113: QTAILQ_ENTRY(CachedL2Table) node;
114: int ref;
115: } CachedL2Table;
116:
117: typedef struct {
118: QTAILQ_HEAD(, CachedL2Table) entries;
119: unsigned int n_entries;
120: } L2TableCache;
121:
122: typedef struct QEDRequest {
123: CachedL2Table *l2_table;
124: } QEDRequest;
125:
126: typedef struct QEDAIOCB {
127: BlockDriverAIOCB common;
128: QEMUBH *bh;
129: int bh_ret; /* final return status for completion bh */
130: QSIMPLEQ_ENTRY(QEDAIOCB) next; /* next request */
131: bool is_write; /* false - read, true - write */
132: bool *finished; /* signal for cancel completion */
133: uint64_t end_pos; /* request end on block device, in bytes */
134:
135: /* User scatter-gather list */
136: QEMUIOVector *qiov;
137: size_t qiov_offset; /* byte count already processed */
138:
139: /* Current cluster scatter-gather list */
140: QEMUIOVector cur_qiov;
141: uint64_t cur_pos; /* position on block device, in bytes */
142: uint64_t cur_cluster; /* cluster offset in image file */
143: unsigned int cur_nclusters; /* number of clusters being accessed */
144: int find_cluster_ret; /* used for L1/L2 update */
145:
146: QEDRequest request;
147: } QEDAIOCB;
148:
149: typedef struct {
150: BlockDriverState *bs; /* device */
151: uint64_t file_size; /* length of image file, in bytes */
152:
153: QEDHeader header; /* always cpu-endian */
154: QEDTable *l1_table;
155: L2TableCache l2_cache; /* l2 table cache */
156: uint32_t table_nelems;
157: uint32_t l1_shift;
158: uint32_t l2_shift;
159: uint32_t l2_mask;
160:
161: /* Allocating write request queue */
162: QSIMPLEQ_HEAD(, QEDAIOCB) allocating_write_reqs;
1.1.1.3 ! root 163: bool allocating_write_reqs_plugged;
! 164:
! 165: /* Periodic flush and clear need check flag */
! 166: QEMUTimer *need_check_timer;
1.1 root 167: } BDRVQEDState;
168:
169: enum {
170: QED_CLUSTER_FOUND, /* cluster found */
1.1.1.3 ! root 171: QED_CLUSTER_ZERO, /* zero cluster found */
1.1 root 172: QED_CLUSTER_L2, /* cluster missing in L2 */
173: QED_CLUSTER_L1, /* cluster missing in L1 */
174: };
175:
176: /**
177: * qed_find_cluster() completion callback
178: *
179: * @opaque: User data for completion callback
180: * @ret: QED_CLUSTER_FOUND Success
181: * QED_CLUSTER_L2 Data cluster unallocated in L2
182: * QED_CLUSTER_L1 L2 unallocated in L1
183: * -errno POSIX error occurred
184: * @offset: Data cluster offset
185: * @len: Contiguous bytes starting from cluster offset
186: *
187: * This function is invoked when qed_find_cluster() completes.
188: *
189: * On success ret is QED_CLUSTER_FOUND and offset/len are a contiguous range
190: * in the image file.
191: *
192: * On failure ret is QED_CLUSTER_L2 or QED_CLUSTER_L1 for missing L2 or L1
193: * table offset, respectively. len is number of contiguous unallocated bytes.
194: */
195: typedef void QEDFindClusterFunc(void *opaque, int ret, uint64_t offset, size_t len);
196:
197: /**
198: * Generic callback for chaining async callbacks
199: */
200: typedef struct {
201: BlockDriverCompletionFunc *cb;
202: void *opaque;
203: } GenericCB;
204:
205: void *gencb_alloc(size_t len, BlockDriverCompletionFunc *cb, void *opaque);
206: void gencb_complete(void *opaque, int ret);
207:
208: /**
209: * L2 cache functions
210: */
211: void qed_init_l2_cache(L2TableCache *l2_cache);
212: void qed_free_l2_cache(L2TableCache *l2_cache);
213: CachedL2Table *qed_alloc_l2_cache_entry(L2TableCache *l2_cache);
214: void qed_unref_l2_cache_entry(CachedL2Table *entry);
215: CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset);
216: void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table);
217:
218: /**
219: * Table I/O functions
220: */
221: int qed_read_l1_table_sync(BDRVQEDState *s);
222: void qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n,
223: BlockDriverCompletionFunc *cb, void *opaque);
224: int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
225: unsigned int n);
226: int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
227: uint64_t offset);
228: void qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset,
229: BlockDriverCompletionFunc *cb, void *opaque);
230: void qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
231: unsigned int index, unsigned int n, bool flush,
232: BlockDriverCompletionFunc *cb, void *opaque);
233: int qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
234: unsigned int index, unsigned int n, bool flush);
235:
236: /**
237: * Cluster functions
238: */
239: void qed_find_cluster(BDRVQEDState *s, QEDRequest *request, uint64_t pos,
240: size_t len, QEDFindClusterFunc *cb, void *opaque);
241:
242: /**
243: * Consistency check
244: */
245: int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix);
246:
247: QEDTable *qed_alloc_table(BDRVQEDState *s);
248:
249: /**
250: * Round down to the start of a cluster
251: */
252: static inline uint64_t qed_start_of_cluster(BDRVQEDState *s, uint64_t offset)
253: {
254: return offset & ~(uint64_t)(s->header.cluster_size - 1);
255: }
256:
257: static inline uint64_t qed_offset_into_cluster(BDRVQEDState *s, uint64_t offset)
258: {
259: return offset & (s->header.cluster_size - 1);
260: }
261:
1.1.1.2 root 262: static inline uint64_t qed_bytes_to_clusters(BDRVQEDState *s, uint64_t bytes)
1.1 root 263: {
264: return qed_start_of_cluster(s, bytes + (s->header.cluster_size - 1)) /
265: (s->header.cluster_size - 1);
266: }
267:
268: static inline unsigned int qed_l1_index(BDRVQEDState *s, uint64_t pos)
269: {
270: return pos >> s->l1_shift;
271: }
272:
273: static inline unsigned int qed_l2_index(BDRVQEDState *s, uint64_t pos)
274: {
275: return (pos >> s->l2_shift) & s->l2_mask;
276: }
277:
278: /**
279: * Test if a cluster offset is valid
280: */
281: static inline bool qed_check_cluster_offset(BDRVQEDState *s, uint64_t offset)
282: {
283: uint64_t header_size = (uint64_t)s->header.header_size *
284: s->header.cluster_size;
285:
286: if (offset & (s->header.cluster_size - 1)) {
287: return false;
288: }
289: return offset >= header_size && offset < s->file_size;
290: }
291:
292: /**
293: * Test if a table offset is valid
294: */
295: static inline bool qed_check_table_offset(BDRVQEDState *s, uint64_t offset)
296: {
297: uint64_t end_offset = offset + (s->header.table_size - 1) *
298: s->header.cluster_size;
299:
300: /* Overflow check */
301: if (end_offset <= offset) {
302: return false;
303: }
304:
305: return qed_check_cluster_offset(s, offset) &&
306: qed_check_cluster_offset(s, end_offset);
307: }
308:
1.1.1.3 ! root 309: static inline bool qed_offset_is_cluster_aligned(BDRVQEDState *s,
! 310: uint64_t offset)
! 311: {
! 312: if (qed_offset_into_cluster(s, offset)) {
! 313: return false;
! 314: }
! 315: return true;
! 316: }
! 317:
! 318: static inline bool qed_offset_is_unalloc_cluster(uint64_t offset)
! 319: {
! 320: if (offset == 0) {
! 321: return true;
! 322: }
! 323: return false;
! 324: }
! 325:
! 326: static inline bool qed_offset_is_zero_cluster(uint64_t offset)
! 327: {
! 328: if (offset == 1) {
! 329: return true;
! 330: }
! 331: return false;
! 332: }
! 333:
1.1 root 334: #endif /* BLOCK_QED_H */
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