Messages in this thread | | | Date | Mon, 04 Dec 2006 15:46:33 -0500 | From | Wendy Cheng <> | Subject | Re: [PATCH] prune_icache_sb |
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Russell Cattelan wrote: > Wendy Cheng wrote: > >> Linux kernel, particularly the VFS layer, is starting to show signs >> of inadequacy as the software components built upon it keep growing. >> I have doubts that it can keep up and handle this complexity with a >> development policy like you just described (filesystem is a dumb >> layer ?). Aren't these DIO_xxx_LOCKING flags inside >> __blockdev_direct_IO() a perfect example why trying to do too many >> things inside vfs layer for so many filesystems is a bad idea ? By >> the way, since we're on this subject, could we discuss a little bit >> about vfs rename call (or I can start another new discussion thread) ? >> >> Note that linux do_rename() starts with the usual lookup logic, >> followed by "lock_rename", then a final round of dentry lookup, and >> finally comes to filesystem's i_op->rename call. Since lock_rename() >> only calls for vfs layer locks that are local to this particular >> machine, for a cluster filesystem, there exists a huge window between >> the final lookup and filesystem's i_op->rename calls such that the >> file could get deleted from another node before fs can do anything >> about it. Is it possible that we could get a new function pointer >> (lock_rename) in inode_operations structure so a cluster filesystem >> can do proper locking ? > > It looks like the ocfs2 guys have the similar problem? > > http://ftp.kernel.org/pub/linux/kernel/people/mfasheh/ocfs2/ocfs2_git_patches/ocfs2-upstream-linus-20060924/0009-PATCH-Allow-file-systems-to-manually-d_move-inside-of-rename.txt > > >
Thanks for the pointer. Same as ocfs2, under current VFS code, both GFS1/2 also need FS_ODD_RENAME flag for the rename problem - got an ugly ~200 line draft patch ready for GFS1 (and am looking into GFS2 at this moment). The issue here is, for GFS, if vfs lock_rename() can call us, this complication can be greatly reduced. Will start another thread to see whether the wish can be granted.
-- Wendy
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