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Wong" To: Brian Foster Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, hch@infradead.org, willy@infradead.org Subject: Re: [PATCH v3 2/7] iomap: remove pos+len BUG_ON() to after folio lookup Message-ID: <20250715051435.GM2672049@frogsfrogsfrogs> References: <20250714204122.349582-1-bfoster@redhat.com> <20250714204122.349582-3-bfoster@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250714204122.349582-3-bfoster@redhat.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 335FC40009 X-Stat-Signature: fuskm1ky4n3dy6quzr6ci3z5ogy8nenh X-Rspam-User: X-HE-Tag: 1752556477-861227 X-HE-Meta: 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 1jObxT8e +JfjyZdk5FQMsLAlIw3SisITC0RSk4NAkJjik28al9ODJZH7mRLcwqZlh4A9l3hAtVDJ5+Y1qY2OsT6O/w+B/e4tPi7o0wKMSV1W9d5lBwmBBK4MMJ7QW2y44ir7r1TE31itLVZ2z2jIMj+m6H47FDO9PN/7CLM67f9BoreCHAa9fdBM6L7I3+kaF2nyrivoYZ2+3LqCtzZ8wIbHvCGqLPUwhO7D9yxWEycyXZLUBgH4yZU+x9HVceniZ+rU3qt77LXKyoF8G4DFqO3a4KmeQ6jDfCaIeFL1fucAvdXtyiOXhc8iDjKg6Zq7nhCt3Nm8IMJzQiMihi9HIc9CXcwdbiGQhNA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 14, 2025 at 04:41:17PM -0400, Brian Foster wrote: > The bug checks at the top of iomap_write_begin() assume the pos/len > reflect exactly the next range to process. This may no longer be the > case once the get folio path is able to process a folio batch from > the filesystem. On top of that, len is already trimmed to within the > iomap/srcmap by iomap_length(), so these checks aren't terribly > useful. Remove the unnecessary BUG_ON() checks. > > Signed-off-by: Brian Foster > Reviewed-by: Christoph Hellwig Heh, glad this went away Reviewed-by: "Darrick J. Wong" --D > --- > fs/iomap/buffered-io.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 3729391a18f3..38da2fa6e6b0 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -805,15 +805,12 @@ static int iomap_write_begin(struct iomap_iter *iter, struct folio **foliop, > { > const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops; > const struct iomap *srcmap = iomap_iter_srcmap(iter); > - loff_t pos = iter->pos; > + loff_t pos; > u64 len = min_t(u64, SIZE_MAX, iomap_length(iter)); > struct folio *folio; > int status = 0; > > len = min_not_zero(len, *plen); > - BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length); > - if (srcmap != &iter->iomap) > - BUG_ON(pos + len > srcmap->offset + srcmap->length); > > if (fatal_signal_pending(current)) > return -EINTR; > -- > 2.50.0 > >