From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id A9EF77F3F for ; Tue, 24 Mar 2015 07:07:29 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay3.corp.sgi.com (Postfix) with ESMTP id 465ABAC003 for ; Tue, 24 Mar 2015 05:07:26 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id mZTzJfcBN1LIDocF (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Tue, 24 Mar 2015 05:07:25 -0700 (PDT) Date: Tue, 24 Mar 2015 08:07:23 -0400 From: Brian Foster Subject: Re: [PATCH 01/13 V2] xfs_db: Allow writes of corrupted data by optionally skipping write verifiers Message-ID: <20150324120722.GA21657@bfoster.bfoster> References: <1426624395-8258-1-git-send-email-sandeen@redhat.com> <1426624395-8258-2-git-send-email-sandeen@redhat.com> <551070CC.9040309@sandeen.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <551070CC.9040309@sandeen.net> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: Eric Sandeen , xfs@oss.sgi.com On Mon, Mar 23, 2015 at 03:00:12PM -0500, Eric Sandeen wrote: > Being able to write corrupt data is handy if we wish to test > repair against specific types of corruptions. > > Add a "-c" option to the write command which allows this by removing > the write verifier. > > Note that this also skips CRC updates; it's not currently possible > to write invalid data with a valid CRC; CRC recalculation is > intertwined with validation. > > Signed-off-by: Eric Sandeen > --- Reviewed-by: Brian Foster > > V2: Fix whitespace, remove "if (argc)", and test for > iocur_top->bp->b_ops before attempting to deref it. > > diff --git a/db/io.c b/db/io.c > index 7f1b76a..c5898f1 100644 > --- a/db/io.c > +++ b/db/io.c > @@ -457,6 +457,13 @@ write_cur_bbs(void) > } > > void > +xfs_dummy_verify( > + struct xfs_buf *bp) > +{ > + return; > +} > + > +void > write_cur(void) > { > if (iocur_sp < 0) { > diff --git a/db/io.h b/db/io.h > index 71082e6..31d96b4 100644 > --- a/db/io.h > +++ b/db/io.h > @@ -63,6 +63,7 @@ extern void set_cur(const struct typ *t, __int64_t d, int c, int ring_add, > bbmap_t *bbmap); > extern void ring_add(void); > extern void set_iocur_type(const struct typ *t); > +extern void xfs_dummy_verify(struct xfs_buf *bp); > > /* > * returns -1 for unchecked, 0 for bad and 1 for good > diff --git a/db/write.c b/db/write.c > index a0f14f4..655b618 100644 > --- a/db/write.c > +++ b/db/write.c > @@ -38,7 +38,7 @@ static int write_f(int argc, char **argv); > static void write_help(void); > > static const cmdinfo_t write_cmd = > - { "write", NULL, write_f, 0, -1, 0, N_("[field or value]..."), > + { "write", NULL, write_f, 0, -1, 0, N_("[-c] [field or value]..."), > N_("write value to disk"), write_help }; > > void > @@ -79,6 +79,7 @@ write_help(void) > " String mode: 'write \"This_is_a_filename\" - write null terminated string.\n" > "\n" > " In data mode type 'write' by itself for a list of specific commands.\n\n" > +" Specifying the -c option will allow writes of invalid (corrupt) data.\n\n" > )); > > } > @@ -90,6 +91,10 @@ write_f( > { > pfunc_t pf; > extern char *progname; > + int c; > + int corrupt = 0; /* Allow write of corrupt data; skip verification */ > + struct xfs_buf_ops nowrite_ops; > + const struct xfs_buf_ops *stashed_ops = NULL; > > if (x.isreadonly & LIBXFS_ISREADONLY) { > dbprintf(_("%s started in read only mode, writing disabled\n"), > @@ -109,12 +114,34 @@ write_f( > return 0; > } > > - /* move past the "write" command */ > - argc--; > - argv++; > + while ((c = getopt(argc, argv, "c")) != EOF) { > + switch (c) { > + case 'c': > + corrupt = 1; > + break; > + default: > + dbprintf(_("bad option for write command\n")); > + return 0; > + } > + } > + > + argc -= optind; > + argv += optind; > + > + if (iocur_top->bp->b_ops && corrupt) { > + /* Temporarily remove write verifier to write bad data */ > + stashed_ops = iocur_top->bp->b_ops; > + nowrite_ops.verify_read = stashed_ops->verify_read; > + nowrite_ops.verify_write = xfs_dummy_verify; > + iocur_top->bp->b_ops = &nowrite_ops; > + dbprintf(_("Allowing write of corrupted data\n")); > + } > > (*pf)(DB_WRITE, cur_typ->fields, argc, argv); > > + if (stashed_ops) > + iocur_top->bp->b_ops = stashed_ops; > + > return 0; > } > > diff --git a/man/man8/xfs_db.8 b/man/man8/xfs_db.8 > index 4d8d4ff..d527230 100644 > --- a/man/man8/xfs_db.8 > +++ b/man/man8/xfs_db.8 > @@ -711,7 +711,7 @@ and > bits respectively, and their string equivalent reported > (but no modifications are made). > .TP > -.BI "write [" "field value" "] ..." > +.BI "write [\-c] [" "field value" "] ..." > Write a value to disk. > Specific fields can be set in structures (struct mode), > or a block can be set to data values (data mode), > @@ -729,6 +729,12 @@ contents of the block can be shifted or rotated left or right, or filled > with a sequence, a constant value, or a random value. In this mode > .B write > with no arguments gives more information on the allowed commands. > +.RS 1.0i > +.TP 0.4i > +.B \-c > +Skip write verifiers and CRC recalculation; allows invalid data to be written > +to disk. > +.RE > .SH TYPES > This section gives the fields in each structure type and their meanings. > Note that some types of block cover multiple actual structures, > > _______________________________________________ > xfs mailing list > xfs@oss.sgi.com > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs