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[PATCH v8 06/31] block/export/fuse.c: allow writable exports to take RES
From: |
Emanuele Giuseppe Esposito |
Subject: |
[PATCH v8 06/31] block/export/fuse.c: allow writable exports to take RESIZE permission |
Date: |
Thu, 3 Mar 2022 10:15:51 -0500 |
Allow writable exports to get BLK_PERM_RESIZE permission
from creation, in fuse_export_create().
In this way, there is no need to give the permission in
fuse_do_truncate(), which might be run in an iothread.
Permissions should be set only in the main thread, so
in any case if an iothread tries to set RESIZE, it will
be blocked.
Also assert in fuse_do_truncate that if we give the
RESIZE permission we can then restore the original ones.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
---
block/export/fuse.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/block/export/fuse.c b/block/export/fuse.c
index fdda8e3c81..5029e70f84 100644
--- a/block/export/fuse.c
+++ b/block/export/fuse.c
@@ -86,8 +86,8 @@ static int fuse_export_create(BlockExport *blk_exp,
assert(blk_exp_args->type == BLOCK_EXPORT_TYPE_FUSE);
- /* For growable exports, take the RESIZE permission */
- if (args->growable) {
+ /* For growable and writable exports, take the RESIZE permission */
+ if (args->growable || blk_exp_args->writable) {
uint64_t blk_perm, blk_shared_perm;
blk_get_perm(exp->common.blk, &blk_perm, &blk_shared_perm);
@@ -392,14 +392,23 @@ static int fuse_do_truncate(const FuseExport *exp,
int64_t size,
{
uint64_t blk_perm, blk_shared_perm;
BdrvRequestFlags truncate_flags = 0;
- int ret;
+ bool add_resize_perm;
+ int ret, ret_check;
+
+ /* Growable and writable exports have a permanent RESIZE permission */
+ add_resize_perm = !exp->growable && !exp->writable;
if (req_zero_write) {
truncate_flags |= BDRV_REQ_ZERO_WRITE;
}
- /* Growable exports have a permanent RESIZE permission */
- if (!exp->growable) {
+ if (add_resize_perm) {
+
+ if (!qemu_in_main_thread()) {
+ /* Changing permissions like below only works in the main thread */
+ return -EPERM;
+ }
+
blk_get_perm(exp->common.blk, &blk_perm, &blk_shared_perm);
ret = blk_set_perm(exp->common.blk, blk_perm | BLK_PERM_RESIZE,
@@ -412,9 +421,11 @@ static int fuse_do_truncate(const FuseExport *exp, int64_t
size,
ret = blk_truncate(exp->common.blk, size, true, prealloc,
truncate_flags, NULL);
- if (!exp->growable) {
+ if (add_resize_perm) {
/* Must succeed, because we are only giving up the RESIZE permission */
- blk_set_perm(exp->common.blk, blk_perm, blk_shared_perm, &error_abort);
+ ret_check = blk_set_perm(exp->common.blk, blk_perm,
+ blk_shared_perm, &error_abort);
+ assert(ret_check == 0);
}
return ret;
--
2.31.1
- [PATCH v8 00/31] block layer: split block APIs in global state and I/O, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 01/31] main-loop.h: introduce qemu_in_main_thread(), Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 02/31] main loop: macros to mark GS and I/O functions, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 04/31] assertions for block global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 08/31] block/block-backend.c: assertions for block-backend, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 06/31] block/export/fuse.c: allow writable exports to take RESIZE permission,
Emanuele Giuseppe Esposito <=
- [PATCH v8 07/31] include/sysemu/block-backend: split header into I/O and global state (GS) API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 05/31] IO_CODE and IO_OR_GS_CODE for block I/O API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 03/31] include/block/block: split header into I/O and global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 09/31] IO_CODE and IO_OR_GS_CODE for block-backend I/O API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 10/31] block.c: assertions to the block layer permissions API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 12/31] assertions for block_int global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 11/31] include/block/block_int: split header into I/O and global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 16/31] GS and IO CODE macros for blockjob_int.h, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 15/31] include/block/blockjob_int.h: split header into I/O and GS API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 13/31] IO_CODE and IO_OR_GS_CODE for block_int I/O API, Emanuele Giuseppe Esposito, 2022/03/03