diff options
Diffstat (limited to 'block.c')
| -rw-r--r-- | block.c | 299 |
1 files changed, 249 insertions, 50 deletions
@@ -668,7 +668,7 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename, open_flags |= BDRV_O_RDWR; } - bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR); + bs->read_only = !(open_flags & BDRV_O_RDWR); /* Open the image, either directly or using a protocol */ if (drv->bdrv_file_open) { @@ -808,6 +808,10 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags, goto unlink_and_fail; } + if (flags & BDRV_O_RDWR) { + flags |= BDRV_O_ALLOW_RDWR; + } + /* Open the image */ ret = bdrv_open_common(bs, filename, flags, drv); if (ret < 0) { @@ -837,12 +841,6 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags, bdrv_close(bs); return ret; } - if (bs->is_temporary) { - bs->backing_hd->keep_read_only = !(flags & BDRV_O_RDWR); - } else { - /* base image inherits from "parent" */ - bs->backing_hd->keep_read_only = bs->keep_read_only; - } } if (!bdrv_key_required(bs)) { @@ -863,6 +861,238 @@ unlink_and_fail: return ret; } +typedef struct BlockReopenQueueEntry { + bool prepared; + BDRVReopenState state; + QSIMPLEQ_ENTRY(BlockReopenQueueEntry) entry; +} BlockReopenQueueEntry; + +/* + * Adds a BlockDriverState to a simple queue for an atomic, transactional + * reopen of multiple devices. + * + * bs_queue can either be an existing BlockReopenQueue that has had QSIMPLE_INIT + * already performed, or alternatively may be NULL a new BlockReopenQueue will + * be created and initialized. This newly created BlockReopenQueue should be + * passed back in for subsequent calls that are intended to be of the same + * atomic 'set'. + * + * bs is the BlockDriverState to add to the reopen queue. + * + * flags contains the open flags for the associated bs + * + * returns a pointer to bs_queue, which is either the newly allocated + * bs_queue, or the existing bs_queue being used. + * + */ +BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue, + BlockDriverState *bs, int flags) +{ + assert(bs != NULL); + + BlockReopenQueueEntry *bs_entry; + if (bs_queue == NULL) { + bs_queue = g_new0(BlockReopenQueue, 1); + QSIMPLEQ_INIT(bs_queue); + } + + if (bs->file) { + bdrv_reopen_queue(bs_queue, bs->file, flags); + } + + bs_entry = g_new0(BlockReopenQueueEntry, 1); + QSIMPLEQ_INSERT_TAIL(bs_queue, bs_entry, entry); + + bs_entry->state.bs = bs; + bs_entry->state.flags = flags; + + return bs_queue; +} + +/* + * Reopen multiple BlockDriverStates atomically & transactionally. + * + * The queue passed in (bs_queue) must have been built up previous + * via bdrv_reopen_queue(). + * + * Reopens all BDS specified in the queue, with the appropriate + * flags. All devices are prepared for reopen, and failure of any + * device will cause all device changes to be abandonded, and intermediate + * data cleaned up. + * + * If all devices prepare successfully, then the changes are committed + * to all devices. + * + */ +int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) +{ + int ret = -1; + BlockReopenQueueEntry *bs_entry, *next; + Error *local_err = NULL; + + assert(bs_queue != NULL); + + bdrv_drain_all(); + + QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) { + if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, &local_err)) { + error_propagate(errp, local_err); + goto cleanup; + } + bs_entry->prepared = true; + } + + /* If we reach this point, we have success and just need to apply the + * changes + */ + QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) { + bdrv_reopen_commit(&bs_entry->state); + } + + ret = 0; + +cleanup: + QSIMPLEQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { + if (ret && bs_entry->prepared) { + bdrv_reopen_abort(&bs_entry->state); + } + g_free(bs_entry); + } + g_free(bs_queue); + return ret; +} + + +/* Reopen a single BlockDriverState with the specified flags. */ +int bdrv_reopen(BlockDriverState *bs, int bdrv_flags, Error **errp) +{ + int ret = -1; + Error *local_err = NULL; + BlockReopenQueue *queue = bdrv_reopen_queue(NULL, bs, bdrv_flags); + + ret = bdrv_reopen_multiple(queue, &local_err); + if (local_err != NULL) { + error_propagate(errp, local_err); + } + return ret; +} + + +/* + * Prepares a BlockDriverState for reopen. All changes are staged in the + * 'opaque' field of the BDRVReopenState, which is used and allocated by + * the block driver layer .bdrv_reopen_prepare() + * + * bs is the BlockDriverState to reopen + * flags are the new open flags + * queue is the reopen queue + * + * Returns 0 on success, non-zero on error. On error errp will be set + * as well. + * + * On failure, bdrv_reopen_abort() will be called to clean up any data. + * It is the responsibility of the caller to then call the abort() or + * commit() for any other BDS that have been left in a prepare() state + * + */ +int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, + Error **errp) +{ + int ret = -1; + Error *local_err = NULL; + BlockDriver *drv; + + assert(reopen_state != NULL); + assert(reopen_state->bs->drv != NULL); + drv = reopen_state->bs->drv; + + /* if we are to stay read-only, do not allow permission change + * to r/w */ + if (!(reopen_state->bs->open_flags & BDRV_O_ALLOW_RDWR) && + reopen_state->flags & BDRV_O_RDWR) { + error_set(errp, QERR_DEVICE_IS_READ_ONLY, + reopen_state->bs->device_name); + goto error; + } + + + ret = bdrv_flush(reopen_state->bs); + if (ret) { + error_set(errp, ERROR_CLASS_GENERIC_ERROR, "Error (%s) flushing drive", + strerror(-ret)); + goto error; + } + + if (drv->bdrv_reopen_prepare) { + ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err); + if (ret) { + if (local_err != NULL) { + error_propagate(errp, local_err); + } else { + error_set(errp, QERR_OPEN_FILE_FAILED, + reopen_state->bs->filename); + } + goto error; + } + } else { + /* It is currently mandatory to have a bdrv_reopen_prepare() + * handler for each supported drv. */ + error_set(errp, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED, + drv->format_name, reopen_state->bs->device_name, + "reopening of file"); + ret = -1; + goto error; + } + + ret = 0; + +error: + return ret; +} + +/* + * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and + * makes them final by swapping the staging BlockDriverState contents into + * the active BlockDriverState contents. + */ +void bdrv_reopen_commit(BDRVReopenState *reopen_state) +{ + BlockDriver *drv; + + assert(reopen_state != NULL); + drv = reopen_state->bs->drv; + assert(drv != NULL); + + /* If there are any driver level actions to take */ + if (drv->bdrv_reopen_commit) { + drv->bdrv_reopen_commit(reopen_state); + } + + /* set BDS specific flags now */ + reopen_state->bs->open_flags = reopen_state->flags; + reopen_state->bs->enable_write_cache = !!(reopen_state->flags & + BDRV_O_CACHE_WB); + reopen_state->bs->read_only = !(reopen_state->flags & BDRV_O_RDWR); +} + +/* + * Abort the reopen, and delete and free the staged changes in + * reopen_state + */ +void bdrv_reopen_abort(BDRVReopenState *reopen_state) +{ + BlockDriver *drv; + + assert(reopen_state != NULL); + drv = reopen_state->bs->drv; + assert(drv != NULL); + + if (drv->bdrv_reopen_abort) { + drv->bdrv_reopen_abort(reopen_state); + } +} + + void bdrv_close(BlockDriverState *bs) { bdrv_flush(bs); @@ -1269,13 +1499,11 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix) int bdrv_commit(BlockDriverState *bs) { BlockDriver *drv = bs->drv; - BlockDriver *backing_drv; int64_t sector, total_sectors; int n, ro, open_flags; - int ret = 0, rw_ret = 0; + int ret = 0; uint8_t *buf; char filename[1024]; - BlockDriverState *bs_rw, *bs_ro; if (!drv) return -ENOMEDIUM; @@ -1284,42 +1512,18 @@ int bdrv_commit(BlockDriverState *bs) return -ENOTSUP; } - if (bs->backing_hd->keep_read_only) { - return -EACCES; - } - if (bdrv_in_use(bs) || bdrv_in_use(bs->backing_hd)) { return -EBUSY; } - backing_drv = bs->backing_hd->drv; ro = bs->backing_hd->read_only; strncpy(filename, bs->backing_hd->filename, sizeof(filename)); open_flags = bs->backing_hd->open_flags; if (ro) { - /* re-open as RW */ - bdrv_delete(bs->backing_hd); - bs->backing_hd = NULL; - bs_rw = bdrv_new(""); - rw_ret = bdrv_open(bs_rw, filename, open_flags | BDRV_O_RDWR, - backing_drv); - if (rw_ret < 0) { - bdrv_delete(bs_rw); - /* try to re-open read-only */ - bs_ro = bdrv_new(""); - ret = bdrv_open(bs_ro, filename, open_flags & ~BDRV_O_RDWR, - backing_drv); - if (ret < 0) { - bdrv_delete(bs_ro); - /* drive not functional anymore */ - bs->drv = NULL; - return ret; - } - bs->backing_hd = bs_ro; - return rw_ret; + if (bdrv_reopen(bs->backing_hd, open_flags | BDRV_O_RDWR, NULL)) { + return -EACCES; } - bs->backing_hd = bs_rw; } total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; @@ -1356,20 +1560,8 @@ ro_cleanup: g_free(buf); if (ro) { - /* re-open as RO */ - bdrv_delete(bs->backing_hd); - bs->backing_hd = NULL; - bs_ro = bdrv_new(""); - ret = bdrv_open(bs_ro, filename, open_flags & ~BDRV_O_RDWR, - backing_drv); - if (ret < 0) { - bdrv_delete(bs_ro); - /* drive not functional anymore */ - bs->drv = NULL; - return ret; - } - bs->backing_hd = bs_ro; - bs->backing_hd->keep_read_only = 0; + /* ignoring error return here */ + bdrv_reopen(bs->backing_hd, open_flags & ~BDRV_O_RDWR, NULL); } return ret; @@ -2168,6 +2360,13 @@ int bdrv_enable_write_cache(BlockDriverState *bs) void bdrv_set_enable_write_cache(BlockDriverState *bs, bool wce) { bs->enable_write_cache = wce; + + /* so a reopen() will preserve wce */ + if (wce) { + bs->open_flags |= BDRV_O_CACHE_WB; + } else { + bs->open_flags &= ~BDRV_O_CACHE_WB; + } } int bdrv_is_encrypted(BlockDriverState *bs) |