From: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx> Add RWF_ATOMIC flag description for pwritev2(). Signed-off-by: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx> #jpg: complete rewrite Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx> --- man2/readv.2 | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/man2/readv.2 b/man2/readv.2 index fa9b0e4e44a2..ff09f3bc9792 100644 --- a/man2/readv.2 +++ b/man2/readv.2 @@ -193,6 +193,51 @@ which provides lower latency, but may use additional resources. .B O_DIRECT flag.) .TP +.BR RWF_ATOMIC " (since Linux 6.7)" +Allows block-based filesystems to indicate that write operations will be issued +with torn-write protection. Torn-write protection means that for a power or any +other hardware failure, all or none of the data from the write will be stored, +but never a mix of old and new data. This flag is meaningful only for +.BR pwritev2 (), +and its effect applies only to the data range written by the system call. +The total write length must be power-of-2 and must be sized between +stx_atomic_write_unit_min and stx_atomic_write_unit_max, both inclusive. The +write must be at a natural offset within the file with respect to the total +write length. Torn-write protection only works with +.B O_DIRECT +flag, i.e. buffered writes are not supported. To guarantee consistency from +the write between a file's in-core state with the storage device, +.BR fdatasync (2) +or +.BR fsync (2) +or +.BR open (2) +and +.B O_SYNC +or +.B O_DSYNC +or +.B pwritev2 () +flag +.B RWF_SYNC +or +.B RWF_DSYNC +is required. +For when regular files are opened with +.BR open (2) +but without +.B O_SYNC +or +.B O_DSYNC +and the +.BR pwritev2() +call is made without +.B RWF_SYNC +or +.BR RWF_DSYNC +set, the range metadata must already be flushed to storage and the data range +must not be in unwritten state, shared, a preallocation, or a hole. +.TP .BR RWF_SYNC " (since Linux 4.7)" .\" commit e864f39569f4092c2b2bc72c773b6e486c7e3bd9 Provide a per-write equivalent of the -- 2.31.1
