Date: Mon, 21 Aug 2006 16:44:21 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Eric Anderson <anderson@centtech.com> Cc: freebsd-fs@freebsd.org, tegge@freebsd.org Subject: Re: Deadlock between nfsd and snapshots. Message-ID: <20060821134421.GC56637@deviant.kiev.zoral.com.ua> In-Reply-To: <44E9B722.2040407@centtech.com> References: <20060817170314.GA17490@peter.osted.lan> <20060818164903.GF20768@deviant.kiev.zoral.com.ua> <20060818.202001.74745664.Tor.Egge@cvsup.no.freebsd.org> <20060821.132151.41668008.Tor.Egge@cvsup.no.freebsd.org> <44E9B722.2040407@centtech.com>
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--WplhKdTI2c8ulnbP Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 21, 2006 at 08:37:38AM -0500, Eric Anderson wrote: > On 08/21/06 08:21, Tor Egge wrote: > >I wrote: > > > >>The deadlock indicates that one or more of IN_CHANGE, IN_MODIFIED or > >>IN_UPDATE was set on the inode, indicating a write operation > >>(e.g. VOP_WRITE(), VOP_RENAME(), VOP_CREATE(), VOP_REMOVE(), VOP_LINK(), > >>VOP_SYMLINK(), VOP_SETATTR(), VOP_MKDIR(), VOP_RMDIR(), VOP_MKNOD()) th= at=20 > >>was > >>not protected by vn_start_write() or vn_start_secondary_write(). > > > >The most common "write" operation was probably VOP_GETATTR(). > > > >ufs_itimes(), called from ufs_getattr(), might set the IN_MODIFIED inode= =20 > >flag > >if IN_ACCESS is set on the inode even if neither IN_CHANGE nor IN_UPDATE= is > >set, transitioning the inode flags into a state where ufs_inactive() cal= ls=20 > >the > >blocking variant of vn_start_secondary_write(). > > > >calling ufs_itimes() with only a shared vnode lock might cause unsafe=20 > >accesses > >to the inode flags. Setting of IN_ACCESS at the end of ffs_read() and > >ffs_extread() might also be unsafe. If DIRECTIO is enabled then O_DIREC= T=20 > >reads > >might not even attempt to set the IN_ACCESS flag. >=20 > Does this mean that setting the noatime flag on mount would dodge this? On the server, yes. --WplhKdTI2c8ulnbP Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFE6bi1C3+MBN1Mb4gRAi0AAKCAMHYgGLM2NiwbeACHYWYcf7KGBACdHaFr bsTADBtxT8QDEPAA9iT0YT0= =ic3w -----END PGP SIGNATURE----- --WplhKdTI2c8ulnbP--
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