| Date | Fri, 19 May 2023 01:09:20 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH v20 03/32] splice: Make direct_read_splice() limit to eof where appropriate |
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On Fri, May 19, 2023 at 08:40:18AM +0100, David Howells wrote: > Make direct_read_splice() limit the read to the end of the file for regular > files and block devices, thereby reducing the amount of allocation it will > do in such a case. > > This means that the blockdev code doesn't require any special handling as > filemap_read_splice() also limits to i_size.
I'm really not sure if this is a good idea. Right now direct_read_splice (which also appears a little misnamed) really is a splice by calling ->read_iter helper. I we don't do any of this validtion we can just call it directly from splice.c instead of calling into ->splice_read for direct I/O and DAX and remove a ton of boilerplate code.
How often do we even call into splice beyond i_size and for how much?
> + if (S_ISREG(file_inode(in)->i_mode) || > + S_ISBLK(file_inode(in)->i_mode)) {
Btw, having these kinds of checks in supposedly generic code is always a marked for a bit of a layering problem.
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