| /* |
| * QEMU Enhanced Disk Format |
| * |
| * Copyright IBM, Corp. 2010 |
| * |
| * Authors: |
| * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> |
| * Anthony Liguori <aliguori@us.ibm.com> |
| * |
| * This work is licensed under the terms of the GNU LGPL, version 2 or later. |
| * See the COPYING.LIB file in the top-level directory. |
| * |
| */ |
| |
| #ifndef BLOCK_QED_H |
| #define BLOCK_QED_H |
| |
| #include "block/block_int.h" |
| |
| /* The layout of a QED file is as follows: |
| * |
| * +--------+----------+----------+----------+-----+ |
| * | header | L1 table | cluster0 | cluster1 | ... | |
| * +--------+----------+----------+----------+-----+ |
| * |
| * There is a 2-level pagetable for cluster allocation: |
| * |
| * +----------+ |
| * | L1 table | |
| * +----------+ |
| * ,------' | '------. |
| * +----------+ | +----------+ |
| * | L2 table | ... | L2 table | |
| * +----------+ +----------+ |
| * ,------' | '------. |
| * +----------+ | +----------+ |
| * | Data | ... | Data | |
| * +----------+ +----------+ |
| * |
| * The L1 table is fixed size and always present. L2 tables are allocated on |
| * demand. The L1 table size determines the maximum possible image size; it |
| * can be influenced using the cluster_size and table_size values. |
| * |
| * All fields are little-endian on disk. |
| */ |
| #define QED_DEFAULT_CLUSTER_SIZE 65536 |
| enum { |
| QED_MAGIC = 'Q' | 'E' << 8 | 'D' << 16 | '\0' << 24, |
| |
| /* The image supports a backing file */ |
| QED_F_BACKING_FILE = 0x01, |
| |
| /* The image needs a consistency check before use */ |
| QED_F_NEED_CHECK = 0x02, |
| |
| /* The backing file format must not be probed, treat as raw image */ |
| QED_F_BACKING_FORMAT_NO_PROBE = 0x04, |
| |
| /* Feature bits must be used when the on-disk format changes */ |
| QED_FEATURE_MASK = QED_F_BACKING_FILE | /* supported feature bits */ |
| QED_F_NEED_CHECK | |
| QED_F_BACKING_FORMAT_NO_PROBE, |
| QED_COMPAT_FEATURE_MASK = 0, /* supported compat feature bits */ |
| QED_AUTOCLEAR_FEATURE_MASK = 0, /* supported autoclear feature bits */ |
| |
| /* Data is stored in groups of sectors called clusters. Cluster size must |
| * be large to avoid keeping too much metadata. I/O requests that have |
| * sub-cluster size will require read-modify-write. |
| */ |
| QED_MIN_CLUSTER_SIZE = 4 * 1024, /* in bytes */ |
| QED_MAX_CLUSTER_SIZE = 64 * 1024 * 1024, |
| |
| /* Allocated clusters are tracked using a 2-level pagetable. Table size is |
| * a multiple of clusters so large maximum image sizes can be supported |
| * without jacking up the cluster size too much. |
| */ |
| QED_MIN_TABLE_SIZE = 1, /* in clusters */ |
| QED_MAX_TABLE_SIZE = 16, |
| QED_DEFAULT_TABLE_SIZE = 4, |
| |
| /* Delay to flush and clean image after last allocating write completes */ |
| QED_NEED_CHECK_TIMEOUT = 5, /* in seconds */ |
| }; |
| |
| typedef struct { |
| uint32_t magic; /* QED\0 */ |
| |
| uint32_t cluster_size; /* in bytes */ |
| uint32_t table_size; /* for L1 and L2 tables, in clusters */ |
| uint32_t header_size; /* in clusters */ |
| |
| uint64_t features; /* format feature bits */ |
| uint64_t compat_features; /* compatible feature bits */ |
| uint64_t autoclear_features; /* self-resetting feature bits */ |
| |
| uint64_t l1_table_offset; /* in bytes */ |
| uint64_t image_size; /* total logical image size, in bytes */ |
| |
| /* if (features & QED_F_BACKING_FILE) */ |
| uint32_t backing_filename_offset; /* in bytes from start of header */ |
| uint32_t backing_filename_size; /* in bytes */ |
| } QEMU_PACKED QEDHeader; |
| |
| typedef struct { |
| uint64_t offsets[0]; /* in bytes */ |
| } QEDTable; |
| |
| /* The L2 cache is a simple write-through cache for L2 structures */ |
| typedef struct CachedL2Table { |
| QEDTable *table; |
| uint64_t offset; /* offset=0 indicates an invalidate entry */ |
| QTAILQ_ENTRY(CachedL2Table) node; |
| int ref; |
| } CachedL2Table; |
| |
| typedef struct { |
| QTAILQ_HEAD(, CachedL2Table) entries; |
| unsigned int n_entries; |
| } L2TableCache; |
| |
| typedef struct QEDRequest { |
| CachedL2Table *l2_table; |
| } QEDRequest; |
| |
| enum { |
| QED_AIOCB_WRITE = 0x0001, /* read or write? */ |
| QED_AIOCB_ZERO = 0x0002, /* zero write, used with QED_AIOCB_WRITE */ |
| }; |
| |
| typedef struct QEDAIOCB { |
| BlockDriverAIOCB common; |
| QEMUBH *bh; |
| int bh_ret; /* final return status for completion bh */ |
| QSIMPLEQ_ENTRY(QEDAIOCB) next; /* next request */ |
| int flags; /* QED_AIOCB_* bits ORed together */ |
| bool *finished; /* signal for cancel completion */ |
| uint64_t end_pos; /* request end on block device, in bytes */ |
| |
| /* User scatter-gather list */ |
| QEMUIOVector *qiov; |
| size_t qiov_offset; /* byte count already processed */ |
| |
| /* Current cluster scatter-gather list */ |
| QEMUIOVector cur_qiov; |
| QEMUIOVector *backing_qiov; |
| uint64_t cur_pos; /* position on block device, in bytes */ |
| uint64_t cur_cluster; /* cluster offset in image file */ |
| unsigned int cur_nclusters; /* number of clusters being accessed */ |
| int find_cluster_ret; /* used for L1/L2 update */ |
| |
| QEDRequest request; |
| } QEDAIOCB; |
| |
| typedef struct { |
| BlockDriverState *bs; /* device */ |
| uint64_t file_size; /* length of image file, in bytes */ |
| |
| QEDHeader header; /* always cpu-endian */ |
| QEDTable *l1_table; |
| L2TableCache l2_cache; /* l2 table cache */ |
| uint32_t table_nelems; |
| uint32_t l1_shift; |
| uint32_t l2_shift; |
| uint32_t l2_mask; |
| |
| /* Allocating write request queue */ |
| QSIMPLEQ_HEAD(, QEDAIOCB) allocating_write_reqs; |
| bool allocating_write_reqs_plugged; |
| |
| /* Periodic flush and clear need check flag */ |
| QEMUTimer *need_check_timer; |
| } BDRVQEDState; |
| |
| enum { |
| QED_CLUSTER_FOUND, /* cluster found */ |
| QED_CLUSTER_ZERO, /* zero cluster found */ |
| QED_CLUSTER_L2, /* cluster missing in L2 */ |
| QED_CLUSTER_L1, /* cluster missing in L1 */ |
| }; |
| |
| /** |
| * qed_find_cluster() completion callback |
| * |
| * @opaque: User data for completion callback |
| * @ret: QED_CLUSTER_FOUND Success |
| * QED_CLUSTER_L2 Data cluster unallocated in L2 |
| * QED_CLUSTER_L1 L2 unallocated in L1 |
| * -errno POSIX error occurred |
| * @offset: Data cluster offset |
| * @len: Contiguous bytes starting from cluster offset |
| * |
| * This function is invoked when qed_find_cluster() completes. |
| * |
| * On success ret is QED_CLUSTER_FOUND and offset/len are a contiguous range |
| * in the image file. |
| * |
| * On failure ret is QED_CLUSTER_L2 or QED_CLUSTER_L1 for missing L2 or L1 |
| * table offset, respectively. len is number of contiguous unallocated bytes. |
| */ |
| typedef void QEDFindClusterFunc(void *opaque, int ret, uint64_t offset, size_t len); |
| |
| /** |
| * Generic callback for chaining async callbacks |
| */ |
| typedef struct { |
| BlockDriverCompletionFunc *cb; |
| void *opaque; |
| } GenericCB; |
| |
| void *gencb_alloc(size_t len, BlockDriverCompletionFunc *cb, void *opaque); |
| void gencb_complete(void *opaque, int ret); |
| |
| /** |
| * Header functions |
| */ |
| int qed_write_header_sync(BDRVQEDState *s); |
| |
| /** |
| * L2 cache functions |
| */ |
| void qed_init_l2_cache(L2TableCache *l2_cache); |
| void qed_free_l2_cache(L2TableCache *l2_cache); |
| CachedL2Table *qed_alloc_l2_cache_entry(L2TableCache *l2_cache); |
| void qed_unref_l2_cache_entry(CachedL2Table *entry); |
| CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset); |
| void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table); |
| |
| /** |
| * Table I/O functions |
| */ |
| int qed_read_l1_table_sync(BDRVQEDState *s); |
| void qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n, |
| BlockDriverCompletionFunc *cb, void *opaque); |
| int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index, |
| unsigned int n); |
| int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request, |
| uint64_t offset); |
| void qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset, |
| BlockDriverCompletionFunc *cb, void *opaque); |
| void qed_write_l2_table(BDRVQEDState *s, QEDRequest *request, |
| unsigned int index, unsigned int n, bool flush, |
| BlockDriverCompletionFunc *cb, void *opaque); |
| int qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request, |
| unsigned int index, unsigned int n, bool flush); |
| |
| /** |
| * Cluster functions |
| */ |
| void qed_find_cluster(BDRVQEDState *s, QEDRequest *request, uint64_t pos, |
| size_t len, QEDFindClusterFunc *cb, void *opaque); |
| |
| /** |
| * Consistency check |
| */ |
| int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix); |
| |
| QEDTable *qed_alloc_table(BDRVQEDState *s); |
| |
| /** |
| * Round down to the start of a cluster |
| */ |
| static inline uint64_t qed_start_of_cluster(BDRVQEDState *s, uint64_t offset) |
| { |
| return offset & ~(uint64_t)(s->header.cluster_size - 1); |
| } |
| |
| static inline uint64_t qed_offset_into_cluster(BDRVQEDState *s, uint64_t offset) |
| { |
| return offset & (s->header.cluster_size - 1); |
| } |
| |
| static inline uint64_t qed_bytes_to_clusters(BDRVQEDState *s, uint64_t bytes) |
| { |
| return qed_start_of_cluster(s, bytes + (s->header.cluster_size - 1)) / |
| (s->header.cluster_size - 1); |
| } |
| |
| static inline unsigned int qed_l1_index(BDRVQEDState *s, uint64_t pos) |
| { |
| return pos >> s->l1_shift; |
| } |
| |
| static inline unsigned int qed_l2_index(BDRVQEDState *s, uint64_t pos) |
| { |
| return (pos >> s->l2_shift) & s->l2_mask; |
| } |
| |
| /** |
| * Test if a cluster offset is valid |
| */ |
| static inline bool qed_check_cluster_offset(BDRVQEDState *s, uint64_t offset) |
| { |
| uint64_t header_size = (uint64_t)s->header.header_size * |
| s->header.cluster_size; |
| |
| if (offset & (s->header.cluster_size - 1)) { |
| return false; |
| } |
| return offset >= header_size && offset < s->file_size; |
| } |
| |
| /** |
| * Test if a table offset is valid |
| */ |
| static inline bool qed_check_table_offset(BDRVQEDState *s, uint64_t offset) |
| { |
| uint64_t end_offset = offset + (s->header.table_size - 1) * |
| s->header.cluster_size; |
| |
| /* Overflow check */ |
| if (end_offset <= offset) { |
| return false; |
| } |
| |
| return qed_check_cluster_offset(s, offset) && |
| qed_check_cluster_offset(s, end_offset); |
| } |
| |
| static inline bool qed_offset_is_cluster_aligned(BDRVQEDState *s, |
| uint64_t offset) |
| { |
| if (qed_offset_into_cluster(s, offset)) { |
| return false; |
| } |
| return true; |
| } |
| |
| static inline bool qed_offset_is_unalloc_cluster(uint64_t offset) |
| { |
| if (offset == 0) { |
| return true; |
| } |
| return false; |
| } |
| |
| static inline bool qed_offset_is_zero_cluster(uint64_t offset) |
| { |
| if (offset == 1) { |
| return true; |
| } |
| return false; |
| } |
| |
| #endif /* BLOCK_QED_H */ |