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X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: /uiPfhFCM3Y9eljRqbg384UGrQaWZcwzz9/KpoYkMUYGWM3cPdI9zpIBrokZChh1PHC+3Gt0P28ardipeGvbmA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR10MB7359 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-01_10,2024-01-31_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 bulkscore=0 malwarescore=0 suspectscore=0 phishscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2402020010 X-Proofpoint-ORIG-GUID: l12KCsZZ1q_G0YJVM84LTv4YZ8FenzMC X-Proofpoint-GUID: l12KCsZZ1q_G0YJVM84LTv4YZ8FenzMC On 2/2/24 00:48, David Sterba wrote: > On Wed, Jan 31, 2024 at 03:48:00PM -0500, Josef Bacik wrote: >> On Wed, Jan 31, 2024 at 11:49:28PM +0800, Anand Jain wrote: >>> This cleanup patch reuses the main file descriptor (fd1) in open_ctree(), >>> and with this change both the test cases (with partition and without >>> partition) now runs fine. >>> >>> I've done an initial tests only, not validated with the multi-device mkfs. >>> More cleanup is possible but pending feedback; marking this patch as an RFC. >> >> I'd like to see the cleaned up version of this patch, but I have a few comments. >> >> 1) I think re-using the fd is reasonable, tho could this just be reworked to >> create the temp-sb and write this to all the devs, close the file >> descriptors, and then call open_ctree? Multiple sequential open-close maybe fine. > This would trigger the udev unnecessarily and could let other processes > to eg. try to mount the device (like systemd did or maybe still does). > This could fail the second open_ctree. I think you are missing the point that when we write the temp-sb, there is no valid BTRFS magic. As a result, the kernel won't get the scan, and systemd won't attempt to mount. However, there will be a udev event (due to the write-close), and in this udev event, we shall have: ID_FS_UUID= This action cleans the /dev/disk/by-uuid directory, which is fine. > That it's all done with one fd > open reduces possible interactions that could be problematic. Hmm reduced possible interactions is problematic? I didn't get this. Here is the sequence of events to help discuss: Consider a single device, for now: fd1 writes zero and temp-sb. fd2 writes good-sb. fd2 closes. fd1 closes. Please note that the fd which wrote zero/temp-sb (fd1) closes last. Per udevadm monitor the change event OR the UUID is missing (depending on the systemd version). ID_FS_UUID= instead of ID_FS_UUID= >> 2) I hate adding another thing into a core file that we'll have to figure out >> how to undo later as we sync more code from the kernel into btrfs-progs, I'm >> not sure if there's a way around this, but thinking harder about adding >> something to disk-io.c that is for userspace only would be good. > > Yeah the open_ctree functions in progs are misplaced in disk-io.c and > are there for historical reasons. We'd need separate file (or maybe > whole compat directory) but for now let it be there, the cleanup is > going to be big. Thanks, Anand