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t0Oei4ac1f8TgOostuOtbz5hzdUjr0mlMYCbAsWrBqnlEz+zJeClMjDPmml9DFk8cGdTQk6RuBrDvi2UbMPYFA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR10MB6374 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-10-05_05,2023-10-02_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 mlxscore=0 bulkscore=0 adultscore=0 mlxlogscore=999 phishscore=0 spamscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2309180000 definitions=main-2310050063 X-Proofpoint-ORIG-GUID: spK9u3dXW_sN1Cn_WIM8VtyMibWKc8YB X-Proofpoint-GUID: spK9u3dXW_sN1Cn_WIM8VtyMibWKc8YB Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 04/10/2023 22:00, Bart Van Assche wrote: >> >> We only care about *PF. The *N variants were cut from the same cloth as >> TRIM and UNMAP. > > Hi Martin, > > Has the following approach been considered? RWF_ATOMIC only guarantees > atomicity. Persistence is not guaranteed without fsync() / fdatasync(). This is the approach taken. Please consult the proposed man pages, where we say that persistence is not guaranteed without O_SYNC/O_DSYNC/fsync()/fdatasync() The only thing which RWF_ATOMIC guarantees is that the write will not be torn. If you see 2.1.4.2.2 Non-volatile requirements in the NVMe spec, it implies that the FUA bit or a flush command is required for persistence. In 4.29.2 Atomic write operations that do not complete in SBC-4, we are told that atomic writes may pend in the device volatile cache and no atomic write data will be written if a power failure causes loss of data from the write. > > I think this would be more friendly towards battery-powered devices > (smartphones). On these devices it can be safe to skip fsync() / > fdatasync() if the battery level is high enough. Thanks, John