diff options
Diffstat (limited to 'block')
-rw-r--r-- | block/preallocate.c | 89 |
1 files changed, 69 insertions, 20 deletions
diff --git a/block/preallocate.c b/block/preallocate.c index 3173d80534..bfb638d8b1 100644 --- a/block/preallocate.c +++ b/block/preallocate.c @@ -75,8 +75,14 @@ typedef struct BDRVPreallocateState { * be invalid (< 0) when we don't have both exclusive BLK_PERM_RESIZE and * BLK_PERM_WRITE permissions on file child. */ + + /* Gives up the resize permission on children when parents don't need it */ + QEMUBH *drop_resize_bh; } BDRVPreallocateState; +static int preallocate_drop_resize(BlockDriverState *bs, Error **errp); +static void preallocate_drop_resize_bh(void *opaque); + #define PREALLOCATE_OPT_PREALLOC_ALIGN "prealloc-align" #define PREALLOCATE_OPT_PREALLOC_SIZE "prealloc-size" static QemuOptsList runtime_opts = { @@ -142,6 +148,7 @@ static int preallocate_open(BlockDriverState *bs, QDict *options, int flags, * For this to work, mark them invalid. */ s->file_end = s->zero_start = s->data_end = -EINVAL; + s->drop_resize_bh = qemu_bh_new(preallocate_drop_resize_bh, bs); ret = bdrv_open_file_child(NULL, options, "file", bs, errp); if (ret < 0) { @@ -193,6 +200,9 @@ static void preallocate_close(BlockDriverState *bs) { BDRVPreallocateState *s = bs->opaque; + qemu_bh_cancel(s->drop_resize_bh); + qemu_bh_delete(s->drop_resize_bh); + if (s->data_end >= 0) { preallocate_truncate_to_real_size(bs, NULL); } @@ -211,6 +221,7 @@ static int preallocate_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, Error **errp) { PreallocateOpts *opts = g_new0(PreallocateOpts, 1); + int ret; if (!preallocate_absorb_opts(opts, reopen_state->options, reopen_state->bs->file->bs, errp)) { @@ -218,6 +229,19 @@ static int preallocate_reopen_prepare(BDRVReopenState *reopen_state, return -EINVAL; } + /* + * Drop the preallocation already here if reopening read-only. The child + * might also be reopened read-only and then scheduling a BH during the + * permission update is too late. + */ + if ((reopen_state->flags & BDRV_O_RDWR) == 0) { + ret = preallocate_drop_resize(reopen_state->bs, errp); + if (ret < 0) { + g_free(opts); + return ret; + } + } + reopen_state->opaque = opts; return 0; @@ -475,41 +499,61 @@ preallocate_co_getlength(BlockDriverState *bs) return ret; } -static int preallocate_check_perm(BlockDriverState *bs, - uint64_t perm, uint64_t shared, Error **errp) +static int preallocate_drop_resize(BlockDriverState *bs, Error **errp) { BDRVPreallocateState *s = bs->opaque; + int ret; - if (s->data_end >= 0 && !can_write_resize(perm)) { - /* - * Lose permissions. - * We should truncate in check_perm, as in set_perm bs->file->perm will - * be already changed, and we should not violate it. - */ - return preallocate_truncate_to_real_size(bs, errp); + if (s->data_end < 0) { + return 0; + } + + /* + * Before switching children to be read-only, truncate them to remove + * the preallocation and let them have the real size. + */ + ret = preallocate_truncate_to_real_size(bs, errp); + if (ret < 0) { + return ret; } + /* + * We'll drop our permissions and will allow other users to take write and + * resize permissions (see preallocate_child_perm). Anyone will be able to + * change the child, so mark all states invalid. We'll regain control if a + * parent requests write access again. + */ + s->data_end = s->file_end = s->zero_start = -EINVAL; + + bdrv_graph_rdlock_main_loop(); + bdrv_child_refresh_perms(bs, bs->file, NULL); + bdrv_graph_rdunlock_main_loop(); + return 0; } +static void preallocate_drop_resize_bh(void *opaque) +{ + /* + * In case of errors, we'll simply keep the exclusive lock on the image + * indefinitely. + */ + preallocate_drop_resize(opaque, NULL); +} + static void preallocate_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared) { BDRVPreallocateState *s = bs->opaque; if (can_write_resize(perm)) { + qemu_bh_cancel(s->drop_resize_bh); if (s->data_end < 0) { s->data_end = s->file_end = s->zero_start = - bdrv_getlength(bs->file->bs); + bs->file->bs->total_sectors * BDRV_SECTOR_SIZE; } } else { - /* - * We drop our permissions, as well as allow shared - * permissions (see preallocate_child_perm), anyone will be able to - * change the child, so mark all states invalid. We'll regain control if - * get good permissions back. - */ - s->data_end = s->file_end = s->zero_start = -EINVAL; + qemu_bh_schedule(s->drop_resize_bh); } } @@ -517,10 +561,16 @@ static void preallocate_child_perm(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { + BDRVPreallocateState *s = bs->opaque; + bdrv_default_perms(bs, c, role, reopen_queue, perm, shared, nperm, nshared); - if (can_write_resize(perm)) { - /* This should come by default, but let's enforce: */ + /* + * We need exclusive write and resize permissions on the child not only when + * the parent can write to it, but also after the parent gave up write + * permissions until preallocate_drop_resize() has completed. + */ + if (can_write_resize(perm) || s->data_end != -EINVAL) { *nperm |= BLK_PERM_WRITE | BLK_PERM_RESIZE; /* @@ -550,7 +600,6 @@ static BlockDriver bdrv_preallocate_filter = { .bdrv_co_flush = preallocate_co_flush, .bdrv_co_truncate = preallocate_co_truncate, - .bdrv_check_perm = preallocate_check_perm, .bdrv_set_perm = preallocate_set_perm, .bdrv_child_perm = preallocate_child_perm, |