Hi, On Thu, 2014-01-16 at 11:10 -0500, J. Bruce Fields wrote: > On Wed, Jan 15, 2014 at 10:17:49AM -0500, bfields wrote: > > From: "J. Bruce Fields" <bfields@xxxxxxxxxx> > > > > d_splice_alias can create duplicate directory aliases (in the !new > > case), or (in the new case) d_move without holding appropriate locks. > > > > d_materialise_unique deals with both of these problems. (The latter > > seems to be dealt by trylocks (see __d_unalias), which look like they > > could cause spurious lookup failures--but that's at least better than > > corrupting the dcache.) > > > > Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> > > --- > > fs/dcache.c | 25 +------------------------ > > 1 file changed, 1 insertion(+), 24 deletions(-) > > > > Only lightly tested.... If this is right, then we can also just ditch > > d_splice_alias completely, and clean up the various d_find_alias's. > > > > I think the only reason we have both d_splice_alias and > > d_materialise_unique is that the former was written for exportable > > filesystems and the latter for distributed filesystems. > > > > But we have at least one exportable filesystem (fuse) using > > d_materialise_unique. And I doubt d_splice_alias was ever completely > > correct even for on-disk filesystems. > > > > Am I missing some subtlety? > > Hm, I just noticed: > > commit 0d0d110720d7960b77c03c9f2597faaff4b484ae > Author: Miklos Szeredi <mszeredi@xxxxxxx> > Date: Mon Sep 16 14:52:00 2013 +0200 > > GFS2: d_splice_alias() can't return error > > unless it was given an IS_ERR(inode), which isn't the case here. So clean > up the unnecessary error handling in gfs2_create_inode(). > > This paves the way for real fixes (hence the stable Cc). > > Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx> > Signed-off-by: Steven Whitehouse <swhiteho@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > > While the statement is true for the current implementation of > d_splice_alias, I don't think it's actually true for any correct > implementation of d_splice_alias, which must be able to return at least > -ELOOP in the directory case. Does gfs2 need fixing? > > --b. Yes, in that case, probably in two places, Steve. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
