iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

netfslib fixes

Browse Source 
-----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEqG5UsNXhtOCrfGQP+7dXa6fLC2sFAmGvhdUACgkQ+7dXa6fL
 C2t41A/+LETrO+UgaAOhikx5XIZbyZTuiiKWg4i63mBhhhn2593h3z0UjDx9XMEi
 XRPTHHhZ0u+uyWN8r2CkdfkrGx3AK/YBuR7s/N/7yQsXfiv1NrqFxU14gd6EK0YC
 hc7nBxLG/EsN913Jc+ttUjw2Lnnv+7A1JyFc4Rv8aS8SXcRPH5ADy7I8SCFet+nC
 JKoVapkTxLX57X+tiCsf+wnuY7b+mRJ7L5uR/f5uweQr2evQ37PCanenoxPi1wCM
 tvkHrmQ73Je4nPY0tuXgtQzMaozuyEEAdhCjgiyOR9EoeCldbVpzY+AWZkx2qog6
 z0oU1hsWYEj/hFc3r4B7MxYziwUpwJHYssiiwjXm8lVUh2BJA9U97dnc3hQfJa8z
 Upg2nCv+/ObpMiX4l9HKDl6WHvMec/VpYPwbsSC5nMysWZrZos6rales9Ougb/eJ
 cl2vs8YLNm87rhHsFWCp5x2LkFRp9SlJkUWVybdl0M6+SWnB38ckqey3m+xhb3DQ
 brCCa+UyG2d6PGkRthl+iF7Zx86blZ4Rm8qD2rec5K1dNiVP3HunsRO5yq4mXuEK
 QM9m0C/hF8k/v7gD0kLI9h7fEiO7JF7+KelxUVoq57P8hcsnjsHQcfMapn+yP4o0
 6Qda9FnLTXnNj/s9ChMAc9mFwdjSzjbqTfiqNK5BKdypjM/2YEc=
 =w/ll
 -----END PGP SIGNATURE-----

Merge tag 'netfs-fixes-20211207' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull netfslib fixes from David Howells:

 - Fix a lockdep warning and potential deadlock. This is takes the
   simple approach of offloading the write-to-cache done from within a
   network filesystem read to a worker thread to avoid taking the
   sb_writer lock from the cache backing filesystem whilst holding the
   mmap lock on an inode from the network filesystem.

   Jan Kara posits a scenario whereby this can cause deadlock[1], though
   it's quite complex and I think requires someone in userspace to
   actually do I/O on the cache files. Matthew Wilcox isn't so certain,
   though[2].

   An alternative way to fix this, suggested by Darrick Wong, might be
   to allow cachefiles to prevent userspace from performing I/O upon the
   file - something like an exclusive open - but that's beyond the scope
   of a fix here if we do want to make such a facility in the future.

 - In some of the error handling paths where netfs_ops->cleanup() is
   called, the arguments are transposed[3]. gcc doesn't complain because
   one of the parameters is void* and one of the values is void*.

Link: https://lore.kernel.org/r/20210922110420.GA21576@quack2.suse.cz/ [1]
Link: https://lore.kernel.org/r/Ya9eDiFCE2fO7K/S@casper.infradead.org/ [2]
Link: https://lore.kernel.org/r/20211207031449.100510-1-jefflexu@linux.alibaba.com/ [3]

* tag 'netfs-fixes-20211207' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  netfs: fix parameter of cleanup()
  netfs: Fix lockdep warning from taking sb_writers whilst holding mmap_lock
This commit is contained in:
Linus Torvalds 2021-12-09 10:49:36 -08:00
commit 2990c89d1d
1 changed files with 8 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
fs/netfs/read_helper.c
View File

@ -354,16 +354,11 @@ static void netfs_rreq_write_to_cache_work(struct work_struct *work)
netfs_rreq_do_write_to_cache(rreq);
}
static void netfs_rreq_write_to_cache(struct netfs_read_request *rreq,
bool was_async)
static void netfs_rreq_write_to_cache(struct netfs_read_request *rreq)
{
if (was_async) {
rreq->work.func = netfs_rreq_write_to_cache_work;
if (!queue_work(system_unbound_wq, &rreq->work))
BUG();
} else {
netfs_rreq_do_write_to_cache(rreq);
}
rreq->work.func = netfs_rreq_write_to_cache_work;
if (!queue_work(system_unbound_wq, &rreq->work))
BUG();
}
/*
@ -558,7 +553,7 @@ again:
wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);
if (test_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags))
return netfs_rreq_write_to_cache(rreq, was_async);
return netfs_rreq_write_to_cache(rreq);
netfs_rreq_completed(rreq, was_async);
}
@ -960,7 +955,7 @@ int netfs_readpage(struct file *file,
rreq = netfs_alloc_read_request(ops, netfs_priv, file);
if (!rreq) {
if (netfs_priv)
ops->cleanup(netfs_priv, folio_file_mapping(folio));
ops->cleanup(folio_file_mapping(folio), netfs_priv);
folio_unlock(folio);
return -ENOMEM;
}
@ -1191,7 +1186,7 @@ have_folio:
goto error;
have_folio_no_wait:
if (netfs_priv)
ops->cleanup(netfs_priv, mapping);
ops->cleanup(mapping, netfs_priv);
*_folio = folio;
_leave(" = 0");
return 0;
@ -1202,7 +1197,7 @@ error:
folio_unlock(folio);
folio_put(folio);
if (netfs_priv)
ops->cleanup(netfs_priv, mapping);
ops->cleanup(mapping, netfs_priv);
_leave(" = %d", ret);
return ret;
}