On Wed, Jul 21, 2010 at 3:23 AM, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote: > On Jul. 20, 2010, 20:30 +0300, "William A. (Andy) Adamson" <androsadamson@xxxxxxxxx> wrote: >> Trond and Fred informed me that kfree under a spin lock is actually >> OK. So, maybe these patches aren't needed. >> >> On the other hand, with these patches we don't hold the spin lock over >> function calls which to my mind is easier to read. Also, the >> free_layout/free_lseg layoutdriver calls may do more than call kfree. > > I'm all for that. > Just document they must not block. > If we ever see that as a requirement we can then change the caller > to drop the spin lock before calling the free method. You might consider the first patch which combines looking up an lseg and allocating the pnfs_layout_type. They are really the same job, and I think it's more clear what is going on. -->Andy > > Beny > >> >> At least, we should document what we expect from the >> free_layout/free_lseg - e.g. no side affects that conflict with being >> called under a spinlock.. >> >> -->Andy >> >> On Tue, Jul 20, 2010 at 1:01 PM, <andros@xxxxxxxxxx> wrote: >>> >>> Fix kfree under spin lock >>> >>> Both put_lseg and put_layout are called under the inode i_lock where the >>> last reference will end up freeing structures. >>> >>> I know there has been a lot of churn in this code, but free'ing under the >>> spin lock is a no-no. >>> In this patch I refactor the layout allocation, combining it with the >>> layout segment lookup code. The new function, pnfs_get_layout_segment takes >>> inode spin lock, and looks to see if the requested range is serviced by an >>> existing layout segment. If the layout has not been allocated, allocate it. >>> If a layout segement is found, reference it and give up the lock. If no >>> layout segment is found, reference the layout for the layoutget call and >>> give up the lock. >>> >>> 0001-SQUASHME-pnfs-submit-alloc-layout-don-t-call-put_lay.patch >>> 0002-SQUASHME-pnfs-submit-use-atomic_dec_and_lock-for-lay.patch >>> >>> Fix the put_lseg under spin lock. >>> 0003-SQUASHME-pnfs-submit-don-t-call-put_lseg-under-spin-.patch >>> >>> Cleanup. >>> 0004-SQUASHME-pnfs-submit-pnfs_release_layout-just-use-in.patch >>> 0005-SQUASHME-pnfs-submit-fix-has_layout-compile-error.patch >>> >>> Tests: >>> CONFIG_NFS_V4_1 set: >>> Connectathon tests pass against GFS2 and pyNFS file layout servers. >>> >>> CONFIG_NFS_V4_1 not set: >>> Connectathon tests pass. >>> >>> -->Andy >>> >>> -- >>> 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 >>> > -- 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
