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dissect-image: try to open device node before activating

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Hopefully decrease the chance that the device is removed soon after
it is detected.
This commit is contained in:
Yu Watanabe 2022-09-17 05:03:24 +09:00
parent 12f5fbdf30
commit f80015ff40
1 changed files with 11 additions and 1 deletions
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12
src/shared/dissect-image.c
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@ -2069,7 +2069,16 @@ static int verity_partition(
* retry a few times before giving up. */ * retry a few times before giving up. */
for (unsigned i = 0; i < N_DEVICE_NODE_LIST_ATTEMPTS; i++) { for (unsigned i = 0; i < N_DEVICE_NODE_LIST_ATTEMPTS; i++) {
_cleanup_(sym_crypt_freep) struct crypt_device *existing_cd = NULL; _cleanup_(sym_crypt_freep) struct crypt_device *existing_cd = NULL;
_cleanup_close_ int fd = -1;
/* First, check if the device already exists. */
fd = open(node, O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY);
if (fd < 0 && !ERRNO_IS_DEVICE_ABSENT(errno))
return log_debug_errno(errno, "Failed to open verity device %s: %m", node);
if (fd >= 0)
goto check; /* The device already exists. Let's check it. */
/* The symlink to the device node does not exist yet. Assume not activated, and let's activate it. */
r = do_crypt_activate_verity(cd, name, verity); r = do_crypt_activate_verity(cd, name, verity);
if (r >= 0) if (r >= 0)
goto success; /* The device is activated. */ goto success; /* The device is activated. */
@ -2087,6 +2096,7 @@ static int verity_partition(
-EBUSY /* Volume is being opened but not ready, crypt_init_by_name() can fetch details. */)) -EBUSY /* Volume is being opened but not ready, crypt_init_by_name() can fetch details. */))
return log_debug_errno(r, "Failed to activate verity device %s: %m", node); return log_debug_errno(r, "Failed to activate verity device %s: %m", node);
check:
if (!restore_deferred_remove){ if (!restore_deferred_remove){
/* To avoid races, disable automatic removal on umount while setting up the new device. Restore it on failure. */ /* To avoid races, disable automatic removal on umount while setting up the new device. Restore it on failure. */
r = dm_deferred_remove_cancel(name); r = dm_deferred_remove_cancel(name);
@ -2115,7 +2125,7 @@ static int verity_partition(
if (r < 0) if (r < 0)
return log_debug_errno(r, "Failed to check if existing verity device %s can be reused: %m", node); return log_debug_errno(r, "Failed to check if existing verity device %s can be reused: %m", node);
if (r >= 0) { /* FIXME: Drop this meaningless condition later. */ if (fd < 0) {
/* devmapper might say that the device exists, but the devlink might not yet have been /* devmapper might say that the device exists, but the devlink might not yet have been
* created. Check and wait for the udev event in that case. */ * created. Check and wait for the udev event in that case. */
r = device_wait_for_devlink(node, "block", verity_timeout(), NULL); r = device_wait_for_devlink(node, "block", verity_timeout(), NULL);