From bca5283bd4a086bcbfaddc024491a400cc9b2fa9 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 17 Jul 2020 12:54:25 +0200 Subject: file-posix: Fix check_hdev_writable() with auto-read-only For Linux block devices, being able to open the device read-write doesn't necessarily mean that the device is actually writable (one example is a read-only LV, as you get with lvchange -pr ). We have check_hdev_writable() to check this condition and fail opening the image read-write if it's not actually writable. However, this check doesn't take auto-read-only into account, but results in a hard failure instead of downgrading to read-only where possible. Fix this and do the writable check not based on BDRV_O_RDWR, but only when this actually results in opening the file read-write. A second check is inserted in raw_reconfigure_getfd() to have the same check when dynamic auto-read-only upgrades an image file from read-only to read-write. Signed-off-by: Kevin Wolf Message-Id: <20200717105426.51134-3-kwolf@redhat.com> Reviewed-by: Max Reitz Signed-off-by: Kevin Wolf --- block/file-posix.c | 33 +++++++++++++++++++++------------ 1 file changed, 21 insertions(+), 12 deletions(-) (limited to 'block/file-posix.c') diff --git a/block/file-posix.c b/block/file-posix.c index dd7dab07d6..996e45ab95 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -425,7 +425,7 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) } } -static int check_hdev_writable(BDRVRawState *s) +static int check_hdev_writable(int fd) { #if defined(BLKROGET) /* Linux block devices can be configured "read-only" using blockdev(8). @@ -439,7 +439,7 @@ static int check_hdev_writable(BDRVRawState *s) struct stat st; int readonly = 0; - if (fstat(s->fd, &st)) { + if (fstat(fd, &st)) { return -errno; } @@ -447,7 +447,7 @@ static int check_hdev_writable(BDRVRawState *s) return 0; } - if (ioctl(s->fd, BLKROGET, &readonly) < 0) { + if (ioctl(fd, BLKROGET, &readonly) < 0) { return -errno; } @@ -642,6 +642,15 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, } s->fd = fd; + /* Check s->open_flags rather than bdrv_flags due to auto-read-only */ + if (s->open_flags & O_RDWR) { + ret = check_hdev_writable(s->fd); + if (ret < 0) { + error_setg_errno(errp, -ret, "The device is not writable"); + goto fail; + } + } + s->perm = 0; s->shared_perm = BLK_PERM_ALL; @@ -1034,6 +1043,15 @@ static int raw_reconfigure_getfd(BlockDriverState *bs, int flags, } } + if (fd != -1 && (*open_flags & O_RDWR)) { + ret = check_hdev_writable(fd); + if (ret < 0) { + qemu_close(fd); + error_setg_errno(errp, -ret, "The device is not writable"); + return -1; + } + } + return fd; } @@ -3478,15 +3496,6 @@ hdev_open_Mac_error: /* Since this does ioctl the device must be already opened */ bs->sg = hdev_is_sg(bs); - if (flags & BDRV_O_RDWR) { - ret = check_hdev_writable(s); - if (ret < 0) { - raw_close(bs); - error_setg_errno(errp, -ret, "The device is not writable"); - return ret; - } - } - return ret; } -- cgit v1.2.3