summaryrefslogtreecommitdiffstats
path: root/include
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2024-05-24 16:26:11 +0200
committerChristian Brauner <brauner@kernel.org>2024-05-27 13:12:13 +0200
commitf89ea63f1c65d3e93b255f14f9d9e05df87955fa (patch)
treed413765b7c77af900f3550e127a3124a9f23ab41 /include
parentafs: Don't cross .backup mountpoint from backup volume (diff)
downloadlinux-f89ea63f1c65d3e93b255f14f9d9e05df87955fa.tar.xz
linux-f89ea63f1c65d3e93b255f14f9d9e05df87955fa.zip
netfs, 9p: Fix race between umount and async request completion
There's a problem in 9p's interaction with netfslib whereby a crash occurs because the 9p_fid structs get forcibly destroyed during client teardown (without paying attention to their refcounts) before netfslib has finished with them. However, it's not a simple case of deferring the clunking that p9_fid_put() does as that requires the p9_client record to still be present. The problem is that netfslib has to unlock pages and clear the IN_PROGRESS flag before destroying the objects involved - including the fid - and, in any case, nothing checks to see if writeback completed barring looking at the page flags. Fix this by keeping a count of outstanding I/O requests (of any type) and waiting for it to quiesce during inode eviction. Reported-by: syzbot+df038d463cca332e8414@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/0000000000005be0aa061846f8d6@google.com/ Reported-by: syzbot+d7c7a495a5e466c031b6@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/000000000000b86c5e06130da9c6@google.com/ Reported-by: syzbot+1527696d41a634cc1819@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/000000000000041f960618206d7e@google.com/ Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/755891.1716560771@warthog.procyon.org.uk Tested-by: syzbot+d7c7a495a5e466c031b6@syzkaller.appspotmail.com Reviewed-by: Dominique Martinet <asmadeus@codewreck.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Jeff Layton <jlayton@kernel.org> cc: Steve French <sfrench@samba.org> cc: Hillf Danton <hdanton@sina.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Reported-and-tested-by: syzbot+d7c7a495a5e466c031b6@syzkaller.appspotmail.com Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/netfs.h18
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index ca56a4428043..3b22ce0d064c 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -68,6 +68,7 @@ struct netfs_inode {
loff_t remote_i_size; /* Size of the remote file */
loff_t zero_point; /* Size after which we assume there's no data
* on the server */
+ atomic_t io_count; /* Number of outstanding reqs */
unsigned long flags;
#define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */
#define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */
@@ -472,6 +473,7 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,
ctx->remote_i_size = i_size_read(&ctx->inode);
ctx->zero_point = LLONG_MAX;
ctx->flags = 0;
+ atomic_set(&ctx->io_count, 0);
#if IS_ENABLED(CONFIG_FSCACHE)
ctx->cache = NULL;
#endif
@@ -515,4 +517,20 @@ static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
#endif
}
+/**
+ * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
+ * @ctx: The netfs inode to wait on
+ *
+ * Wait for outstanding I/O requests of any type to complete. This is intended
+ * to be called from inode eviction routines. This makes sure that any
+ * resources held by those requests are cleaned up before we let the inode get
+ * cleaned up.
+ */
+static inline void netfs_wait_for_outstanding_io(struct inode *inode)
+{
+ struct netfs_inode *ictx = netfs_inode(inode);
+
+ wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
+}
+
#endif /* _LINUX_NETFS_H */