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netfs: Fix read abandonment during retry 

Under certain circumstances, all the remaining subrequests from a read
request will get abandoned during retry.  The abandonment process expects
the 'subreq' variable to be set to the place to start abandonment from, but
it doesn't always have a useful value (it will be uninitialised on the
first pass through the loop and it may point to a deleted subrequest on
later passes).

Fix the first jump to "abandon:" to set subreq to the start of the first
subrequest expected to need retry (which, in this abandonment case, turned
out unexpectedly to no longer have NEED_RETRY set).

Also clear the subreq pointer after discarding superfluous retryable
subrequests to cause an oops if we do try to access it.

Fixes: ee4cdf7ba8 ("netfs: Speed up buffered reading")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/3775287.1773848338@warthog.procyon.org.uk
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
David Howells 2026-03-18 15:38:58 +00:00 committed by Christian Brauner
parent 8fb6857f2f
commit 7e57523490
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1 changed files with 4 additions and 1 deletions
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5
fs/netfs/read_retry.c
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@ -93,8 +93,10 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
from->start, from->transferred, from->len);
if (test_bit(NETFS_SREQ_FAILED, &from->flags) ||
!test_bit(NETFS_SREQ_NEED_RETRY, &from->flags))
!test_bit(NETFS_SREQ_NEED_RETRY, &from->flags)) {
subreq = from;
goto abandon;
}
list_for_each_continue(next, &stream->subrequests) {
subreq = list_entry(next, struct netfs_io_subrequest, rreq_link);
@ -178,6 +180,7 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
if (subreq == to)
break;
}
subreq = NULL;
continue;
}