From d2027745c0ccb9e0f6870b7b0837ff21435d2930 Mon Sep 17 00:00:00 2001 From: Salvatore Bonaccorso Date: Mon, 4 Dec 2017 11:11:28 +0100 Subject: [PATCH 1/2] locks: remove i_have_this_lease check from __break_lease --- ...e-i_have_this_lease-check-from-__break_le.patch | 54 ++++++++++++++++++++++ debian/patches/series | 1 + 2 files changed, 55 insertions(+) create mode 100644 debian/patches/bugfix/all/locks-remove-i_have_this_lease-check-from-__break_le.patch diff --git a/debian/patches/bugfix/all/locks-remove-i_have_this_lease-check-from-__break_le.patch b/debian/patches/bugfix/all/locks-remove-i_have_this_lease-check-from-__break_le.patch new file mode 100644 index 000000000..04a778b40 --- /dev/null +++ b/debian/patches/bugfix/all/locks-remove-i_have_this_lease-check-from-__break_le.patch @@ -0,0 +1,54 @@ +From: Jeff Layton +Date: Mon, 1 Sep 2014 14:27:43 -0400 +Subject: locks: remove i_have_this_lease check from __break_lease +Origin: https://git.kernel.org/linus/843c6b2f4cef384af8e0de6b7ac7191675030e3a + +I think that the intent of this code was to ensure that a process won't +deadlock if it has one fd open with a lease on it and then breaks that +lease by opening another fd. In that case it'll treat the __break_lease +call as if it were non-blocking. + +This seems wrong -- the process could (for instance) be multithreaded +and managing different fds via different threads. I also don't see any +mention of this limitation in the (somewhat sketchy) documentation. + +Remove the check and the non-blocking behavior when i_have_this_lease +is true. + +Signed-off-by: Jeff Layton +[carnil: Backport for 3.16: + - adjust context +] +--- + fs/locks.c | 6 ++---- + 1 file changed, 2 insertions(+), 4 deletions(-) + +--- a/fs/locks.c ++++ b/fs/locks.c +@@ -1326,7 +1326,6 @@ int __break_lease(struct inode *inode, u + struct file_lock *new_fl, *flock; + struct file_lock *fl; + unsigned long break_time; +- int i_have_this_lease = 0; + bool lease_conflict = false; + int want_write = (mode & O_ACCMODE) != O_RDONLY; + +@@ -1346,8 +1345,7 @@ int __break_lease(struct inode *inode, u + for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { + if (leases_conflict(fl, new_fl)) { + lease_conflict = true; +- if (fl->fl_owner == current->files) +- i_have_this_lease = 1; ++ break; + } + } + if (!lease_conflict) +@@ -1377,7 +1375,7 @@ int __break_lease(struct inode *inode, u + fl->fl_lmops->lm_break(fl); + } + +- if (i_have_this_lease || (mode & O_NONBLOCK)) { ++ if (mode & O_NONBLOCK) { + trace_break_lease_noblock(inode, new_fl); + error = -EWOULDBLOCK; + goto out; diff --git a/debian/patches/series b/debian/patches/series index 4cd4a739c..4ab96adb2 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -251,6 +251,7 @@ bugfix/all/vfs-avoid-creation-of-inode-number-0-in-get_next_ino.patch bugfix/all/mm-mmap.c-expand_downwards-don-t-require-the-gap-if-.patch bugfix/x86/mmap-remember-the-map_fixed-flag-as-vm_fixed.patch bugfix/x86/mmap-add-an-exception-to-the-stack-gap-for-hotspot-jvm.patch +bugfix/all/locks-remove-i_have_this_lease-check-from-__break_le.patch # memfd_create() & kdbus backport features/all/kdbus/mm-allow-drivers-to-prevent-new-writable-mappings.patch -- 2.15.1