| Message ID | 20230112155709.303615-5-ammar.faizi@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | liburing updates for 2.4 | expand |
Ammar Faizi <ammarfaizi2@gnuweeb.org> writes: > From: Ammar Faizi <ammarfaizi2@gnuweeb.org> > > I have found two people confused about the io_uring_prep_splice() > function, especially on the offset part. The current manpage for > io_uring_prep_splice() doesn't tell about the rules of the offset > arguments. > > Despite these rules are already noted in "man 2 io_uring_enter", > people who want to know about this prep function will prefer to read > "man 3 io_uring_prep_splice". > > Let's explain it there! Hi Ammar, A few suggestions below: > --- a/man/io_uring_prep_splice.3 > +++ b/man/io_uring_prep_splice.3 > @@ -52,6 +52,34 @@ and > .I fd_in > given as a registered file descriptor offset. > > +If > +.I fd_in > +refers to a pipe, > +.IR off_in > +must be -1. Maybe "off_in is ignored and must be set to -1." > + > +If > +.I fd_in > +does not refer to a pipe and > +.I off_in > +is -1, then bytes are read from bytes -> nbytes ? > +.I fd_in > +starting from the file offset and it is adjusted appropriately. What do you think: starting from the file offset, which is incremented by the number of bytes read. > +If > +.I fd_in > +does not refer to a pipe and > +.I off_in > +is not -1, then the starting offset of > +.I fd_in > +will be > +.IR off_in . > + > +The same rules apply to > +.I fd_out > +and > +.IR off_out . > + > This function prepares an async > .BR splice (2) > request. See that man page for details. > @@ -78,3 +106,13 @@ field. > .BR io_uring_submit (3), > .BR io_uring_register (2), > .BR splice (2) > + > +.SH NOTES > +Note that even if > +.I fd_in > +or > +.I fd_out > +refers to a pipe, the splice operation can still failed with failed -> fail Thanks,
On 1/12/23 10:26 AM, Gabriel Krisman Bertazi wrote: > Ammar Faizi <ammarfaizi2@gnuweeb.org> writes: > >> From: Ammar Faizi <ammarfaizi2@gnuweeb.org> >> >> I have found two people confused about the io_uring_prep_splice() >> function, especially on the offset part. The current manpage for >> io_uring_prep_splice() doesn't tell about the rules of the offset >> arguments. >> >> Despite these rules are already noted in "man 2 io_uring_enter", >> people who want to know about this prep function will prefer to read >> "man 3 io_uring_prep_splice". >> >> Let's explain it there! > > Hi Ammar, > > A few suggestions below: [snip] Shoot, missed this. Ammar, can you send a fixup patch with the below suggestions?
diff --git a/man/io_uring_prep_splice.3 b/man/io_uring_prep_splice.3 index cb82ad0..a177bc6 100644 --- a/man/io_uring_prep_splice.3 +++ b/man/io_uring_prep_splice.3 @@ -52,6 +52,34 @@ and .I fd_in given as a registered file descriptor offset. +If +.I fd_in +refers to a pipe, +.IR off_in +must be -1. + +If +.I fd_in +does not refer to a pipe and +.I off_in +is -1, then bytes are read from +.I fd_in +starting from the file offset and it is adjusted appropriately. + +If +.I fd_in +does not refer to a pipe and +.I off_in +is not -1, then the starting offset of +.I fd_in +will be +.IR off_in . + +The same rules apply to +.I fd_out +and +.IR off_out . + This function prepares an async .BR splice (2) request. See that man page for details. @@ -78,3 +106,13 @@ field. .BR io_uring_submit (3), .BR io_uring_register (2), .BR splice (2) + +.SH NOTES +Note that even if +.I fd_in +or +.I fd_out +refers to a pipe, the splice operation can still failed with +.B EINVAL +if one of the fd doesn't explicitly support splice operation, e.g. reading from +terminal is unsupported from kernel 5.7 to 5.11.