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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-12-09 10:49:36 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-12-09 10:49:36 -0800 |
commit | 2990c89d1df457bd623371324998ee849806ddd3 (patch) | |
tree | 4d9a7cff1de560d3038451697c26e7e80e294d2c | |
parent | 3a49cc22d31eccceb856f468be0646faa2d4643f (diff) | |
parent | 3cfef1b612e15a0c2f5b1c9d3f3f31ad72d56fcd (diff) | |
download | linux-misc-2990c89d1df457bd623371324998ee849806ddd3.tar.gz |
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
-rw-r--r-- | fs/netfs/read_helper.c | 21 |
1 files changed, 8 insertions, 13 deletions
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c index 7046f9bdd8dcd..75c76cbb27ccf 100644 --- a/fs/netfs/read_helper.c +++ b/fs/netfs/read_helper.c @@ -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; } |