Messages in this thread Patch in this message | | | Date | Mon, 22 Jun 2020 19:13:38 +0100 | From | Matthew Wilcox <> | Subject | Re: [RFC] Bypass filesystems for reading cached pages |
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On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > I'm fine with not moving that functionality into the VFS. The problem > I have in gfs2 is that taking glocks is really expensive. Part of that > overhead is accidental, but we definitely won't be able to fix it in > the short term. So something like the IOCB_CACHED flag that prevents > generic_file_read_iter from issuing readahead I/O would save the day > for us. Does that idea stand a chance?
For the short-term fix, is switching to a trylock in gfs2_readahead() acceptable?
diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c index 72c9560f4467..6ccd478c81ff 100644 --- a/fs/gfs2/aops.c +++ b/fs/gfs2/aops.c @@ -600,7 +600,7 @@ static void gfs2_readahead(struct readahead_control *rac) struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_holder gh; - gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh); + gfs2_holder_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_TRY, &gh); if (gfs2_glock_nq(&gh)) goto out_uninit; if (!gfs2_is_stuffed(ip))
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