ping^2?
On Mon, Mar 16, 2009 at 02:30:57AM -0400, Christoph Hellwig wrote:
> ping?
>
> On Tue, Feb 24, 2009 at 08:39:02AM -0500, Christoph Hellwig wrote:
> > xfs_getbmap (or rather the formatters called by it) copy out the getbmap
> > structures under the ilock, which can deadlock against mmap. This has
> > been reported via bugzilla a while ago (#717) and has recently also
> > shown up via lockdep.
> >
> > So allocate a temporary buffer to format the kernel getbmap structures
> > into and then copy them out after dropping the locks.
> >
> > A little problem with this is that we limit the number of extents we
> > can copy out by the maximum allocation size, but I see no real way
> > around that.
> >
> >
> > Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> >
> > Index: xfs/fs/xfs/xfs_bmap.c
> > ===================================================================
> > --- xfs.orig/fs/xfs/xfs_bmap.c 2009-02-23 20:38:27.512925014 +0100
> > +++ xfs/fs/xfs/xfs_bmap.c 2009-02-23 20:40:46.720926193 +0100
> > @@ -5867,12 +5867,13 @@ xfs_getbmap(
> > int nexleft; /* # of user extents left */
> > int subnex; /* # of bmapi's can do */
> > int nmap; /* number of map entries */
> > - struct getbmapx out; /* output structure */
> > + struct getbmapx *out; /* output structure */
> > int whichfork; /* data or attr fork */
> > int prealloced; /* this is a file with
> > * preallocated data space */
> > int iflags; /* interface flags */
> > int bmapi_flags; /* flags for xfs_bmapi */
> > + int cur_ext = 0;
> >
> > mp = ip->i_mount;
> > iflags = bmv->bmv_iflags;
> > @@ -5948,6 +5949,13 @@ xfs_getbmap(
> > return XFS_ERROR(EINVAL);
> > bmvend = bmv->bmv_offset + bmv->bmv_length;
> >
> > +
> > + if (bmv->bmv_count > ULONG_MAX / sizeof(struct getbmapx))
> > + return XFS_ERROR(ENOMEM);
> > + out = kmem_zalloc(bmv->bmv_count * sizeof(struct getbmapx), KM_MAYFAIL);
> > + if (!out)
> > + return XFS_ERROR(ENOMEM);
> > +
> > xfs_ilock(ip, XFS_IOLOCK_SHARED);
> > if (whichfork == XFS_DATA_FORK && !(iflags & BMV_IF_DELALLOC)) {
> > if (ip->i_delayed_blks || ip->i_size > ip->i_d.di_size) {
> > @@ -6001,39 +6009,39 @@ xfs_getbmap(
> > ASSERT(nmap <= subnex);
> >
> > for (i = 0; i < nmap && nexleft && bmv->bmv_length; i++) {
> > - int full = 0; /* user array is full */
> > -
> > - out.bmv_oflags = 0;
> > + out[cur_ext].bmv_oflags = 0;
> > if (map[i].br_state == XFS_EXT_UNWRITTEN)
> > - out.bmv_oflags |= BMV_OF_PREALLOC;
> > + out[cur_ext].bmv_oflags |= BMV_OF_PREALLOC;
> > else if (map[i].br_startblock == DELAYSTARTBLOCK)
> > - out.bmv_oflags |= BMV_OF_DELALLOC;
> > - out.bmv_offset = XFS_FSB_TO_BB(mp, map[i].br_startoff);
> > - out.bmv_length = XFS_FSB_TO_BB(mp,
> > map[i].br_blockcount);
> > - out.bmv_unused1 = out.bmv_unused2 = 0;
> > + out[cur_ext].bmv_oflags |= BMV_OF_DELALLOC;
> > + out[cur_ext].bmv_offset =
> > + XFS_FSB_TO_BB(mp, map[i].br_startoff);
> > + out[cur_ext].bmv_length =
> > + XFS_FSB_TO_BB(mp, map[i].br_blockcount);
> > + out[cur_ext].bmv_unused1 = 0;
> > + out[cur_ext].bmv_unused2 = 0;
> > ASSERT(((iflags & BMV_IF_DELALLOC) != 0) ||
> > (map[i].br_startblock != DELAYSTARTBLOCK));
> > if (map[i].br_startblock == HOLESTARTBLOCK &&
> > whichfork == XFS_ATTR_FORK) {
> > /* came to the end of attribute fork */
> > - out.bmv_oflags |= BMV_OF_LAST;
> > + out[cur_ext].bmv_oflags |= BMV_OF_LAST;
> > goto out_free_map;
> > }
> >
> > - if (!xfs_getbmapx_fix_eof_hole(ip, &out, prealloced,
> > - bmvend, map[i].br_startblock))
> > + if (!xfs_getbmapx_fix_eof_hole(ip, &out[cur_ext],
> > + prealloced, bmvend,
> > + map[i].br_startblock))
> > goto out_free_map;
> >
> > - /* format results & advance arg */
> > - error = formatter(&arg, &out, &full);
> > - if (error || full)
> > - goto out_free_map;
> > nexleft--;
> > bmv->bmv_offset =
> > - out.bmv_offset + out.bmv_length;
> > + out[cur_ext].bmv_offset +
> > + out[cur_ext].bmv_length;
> > bmv->bmv_length =
> > max_t(__int64_t, 0, bmvend - bmv->bmv_offset);
> > bmv->bmv_entries++;
> > + cur_ext++;
> > }
> > } while (nmap && nexleft && bmv->bmv_length);
> >
> > @@ -6043,6 +6051,16 @@ xfs_getbmap(
> > xfs_iunlock_map_shared(ip, lock);
> > out_unlock_iolock:
> > xfs_iunlock(ip, XFS_IOLOCK_SHARED);
> > +
> > + for (i = 0; i < cur_ext; i++) {
> > + int full = 0; /* user array is full */
> > +
> > + /* format results & advance arg */
> > + error = formatter(&arg, &out[i], &full);
> > + if (error || full)
> > + break;
> > + }
> > +
> > return error;
> > }
> >
> >
> > _______________________________________________
> > xfs mailing list
> > xfs@xxxxxxxxxxx
> > http://oss.sgi.com/mailman/listinfo/xfs
> ---end quoted text---
>
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs
---end quoted text---
|