From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?P=c3=a1draig_Brady?= Subject: Re: [PATCH v5 8/9] vfs: Add vfs_copy_file_range() support for pagecache copies Date: Fri, 9 Oct 2015 12:15:53 +0100 Message-ID: <5617A1E9.1080509@draigBrady.com> References: <1443634014-3026-1-git-send-email-Anna.Schumaker@Netapp.com> <1443634014-3026-9-git-send-email-Anna.Schumaker@Netapp.com> <87vbai6sud.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <87vbai6sud.fsf@notabene.neil.brown.name> Sender: linux-btrfs-owner@vger.kernel.org To: Neil Brown , Anna Schumaker , linux-nfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, zab@zabbo.net, viro@zeniv.linux.org.uk, clm@fb.com, darrick.wong@oracle.com, mtk.manpages@gmail.com, andros@netapp.com, hch@infradead.org List-Id: linux-api@vger.kernel.org On 08/10/15 02:40, Neil Brown wrote: > Anna Schumaker writes: >=20 >> @@ -1338,34 +1362,26 @@ ssize_t vfs_copy_file_range(struct file *fil= e_in, loff_t pos_in, >> struct file *file_out, loff_t pos_out, >> size_t len, unsigned int flags) >> { >> - struct inode *inode_in; >> - struct inode *inode_out; >> ssize_t ret; >> =20 >> - if (flags) >> + /* Flags should only be used exclusively. */ >> + if ((flags & COPY_FR_COPY) && (flags & ~COPY_FR_COPY)) >> + return -EINVAL; >> + if ((flags & COPY_FR_REFLINK) && (flags & ~COPY_FR_REFLINK)) >> + return -EINVAL; >> + if ((flags & COPY_FR_DEDUP) && (flags & ~COPY_FR_DEDUP)) >> return -EINVAL; >> =20 >=20 > Do you also need: >=20 > if (flags & ~(COPY_FR_COPY | COPY_FR_REFLINK | COPY_FR_DEDUP)) > return -EINVAL; >=20 > so that future user-space can test if the kernel supports new flags? Seems like a good idea, yes. Also that got me thinking about COPY_FR_SPARSE. What's the current behavior when copying a sparse range? Is the hole propagated by default (good), or is it expanded? Note cp(1) has --sparse=3D{never,auto,always}. Auto is the default, so it would be good I think if that was the default mode for copy_file_= range(). With other sparse modes, we'd have to avoid copy_file_range() unless there was control possible with COPY_FR_SPARSE_{AUTO,NONE,ALWAYS}. Note currently cp --sparse=3Dalways will detect runs of zeros and also avoid speculative preallocation by using fallocate (fd, FALLOC_FL_PUNCH= _HOLE, ...) thanks, P=E1draig. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html