From 9c5e6594f15b7364624a3ad40306c396c93a2145 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 4 May 2017 18:52:40 +0200 Subject: block: Fix write/resize permissions for inactive images Format drivers for inactive nodes don't need write/resize permissions on their bs->file and can share write/resize with another VM (in fact, this is the whole point of keeping images inactive). Represent this fact in the op blocker system, so that image locking does the right thing without special-casing inactive images. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- block.c | 35 +++++++++++++++++++++++++++++++++-- 1 file changed, 33 insertions(+), 2 deletions(-) (limited to 'block.c') diff --git a/block.c b/block.c index 170002e78e..50ba264143 100644 --- a/block.c +++ b/block.c @@ -192,11 +192,20 @@ void path_combine(char *dest, int dest_size, } } +/* Returns whether the image file is opened as read-only. Note that this can + * return false and writing to the image file is still not possible because the + * image is inactivated. */ bool bdrv_is_read_only(BlockDriverState *bs) { return bs->read_only; } +/* Returns whether the image file can be written to right now */ +bool bdrv_is_writable(BlockDriverState *bs) +{ + return !bdrv_is_read_only(bs) && !(bs->open_flags & BDRV_O_INACTIVE); +} + int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, Error **errp) { /* Do not set read_only if copy_on_read is enabled */ @@ -1510,7 +1519,7 @@ static int bdrv_check_perm(BlockDriverState *bs, uint64_t cumulative_perms, /* Write permissions never work with read-only images */ if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && - bdrv_is_read_only(bs)) + !bdrv_is_writable(bs)) { error_setg(errp, "Block node is read-only"); return -EPERM; @@ -1795,7 +1804,7 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c, bdrv_filter_default_perms(bs, c, role, perm, shared, &perm, &shared); /* Format drivers may touch metadata even if the guest doesn't write */ - if (!bdrv_is_read_only(bs)) { + if (bdrv_is_writable(bs)) { perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE; } @@ -1821,6 +1830,10 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c, BLK_PERM_WRITE_UNCHANGED; } + if (bs->open_flags & BDRV_O_INACTIVE) { + shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; + } + *nperm = perm; *nshared = shared; } @@ -3960,6 +3973,7 @@ void bdrv_init_with_whitelist(void) void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp) { BdrvChild *child, *parent; + uint64_t perm, shared_perm; Error *local_err = NULL; int ret; @@ -3996,6 +4010,16 @@ void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp) return; } + /* Update permissions, they may differ for inactive nodes */ + bdrv_get_cumulative_perm(bs, &perm, &shared_perm); + ret = bdrv_check_perm(bs, perm, shared_perm, NULL, &local_err); + if (ret < 0) { + bs->open_flags |= BDRV_O_INACTIVE; + error_propagate(errp, local_err); + return; + } + bdrv_set_perm(bs, perm, shared_perm); + QLIST_FOREACH(parent, &bs->parents, next_parent) { if (parent->role->activate) { parent->role->activate(parent, &local_err); @@ -4040,6 +4064,8 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs, } if (setting_flag) { + uint64_t perm, shared_perm; + bs->open_flags |= BDRV_O_INACTIVE; QLIST_FOREACH(parent, &bs->parents, next_parent) { @@ -4051,6 +4077,11 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs, } } } + + /* Update permissions, they may differ for inactive nodes */ + bdrv_get_cumulative_perm(bs, &perm, &shared_perm); + bdrv_check_perm(bs, perm, shared_perm, NULL, &error_abort); + bdrv_set_perm(bs, perm, shared_perm); } QLIST_FOREACH(child, &bs->children, next) { -- cgit v1.2.3