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authorBrian Behlendorf <[email protected]>2015-12-21 09:27:24 -0800
committerBrian Behlendorf <[email protected]>2015-12-22 16:59:20 -0800
commit2ebc7b72b3989ac53c1753f79eaf71d95419c103 (patch)
treebbbe40243e34ff75c20edc451ce1c0f89f3f50d5 /module/zfs
parent228b461b564532123efbf3f6c595494c8cbe7793 (diff)
Fix z_xattr_lock/z_teardown_lock inversion
There exists a lock inversion between the z_xattr_lock and the z_teardown_lock. Resolve this by taking the z_teardown_lock in all registered xattr callbacks prior to taking the z_xattr_lock. This ensures the locks are always taken is the same order thus preventing a deadlock. Note the z_teardown_lock is taken again in zfs_lookup() and this is safe because the z_teardown lock is a re-entrant read reader/writer lock. * process-1 zpl_xattr_get -> Takes zp->z_xattr_lock __zpl_xattr_get zfs_lookup -> Takes zsb->z_teardown_lock in ZFS_ENTER macro * process-2 zfs_ioc_recv -> Takes zsb->z_teardown_lock in zfs_suspend_fs() zfs_resume_fs zfs_rezget -> Takes zp->z_xattr_lock Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Closes #3943 Closes #3969 Closes #4121
Diffstat (limited to 'module/zfs')
-rw-r--r--module/zfs/zpl_xattr.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/module/zfs/zpl_xattr.c b/module/zfs/zpl_xattr.c
index d224078ef..d9d067305 100644
--- a/module/zfs/zpl_xattr.c
+++ b/module/zfs/zpl_xattr.c
@@ -214,6 +214,7 @@ zpl_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
crhold(cr);
cookie = spl_fstrans_mark();
+ rrm_enter_read(&(zsb)->z_teardown_lock, FTAG);
rw_enter(&zp->z_xattr_lock, RW_READER);
if (zsb->z_use_sa && zp->z_is_sa) {
@@ -230,6 +231,7 @@ zpl_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
out:
rw_exit(&zp->z_xattr_lock);
+ rrm_exit(&(zsb)->z_teardown_lock, FTAG);
spl_fstrans_unmark(cookie);
crfree(cr);
@@ -339,15 +341,18 @@ static int
zpl_xattr_get(struct inode *ip, const char *name, void *value, size_t size)
{
znode_t *zp = ITOZ(ip);
+ zfs_sb_t *zsb = ZTOZSB(zp);
cred_t *cr = CRED();
fstrans_cookie_t cookie;
int error;
crhold(cr);
cookie = spl_fstrans_mark();
+ rrm_enter_read(&(zsb)->z_teardown_lock, FTAG);
rw_enter(&zp->z_xattr_lock, RW_READER);
error = __zpl_xattr_get(ip, name, value, size, cr);
rw_exit(&zp->z_xattr_lock);
+ rrm_exit(&(zsb)->z_teardown_lock, FTAG);
spl_fstrans_unmark(cookie);
crfree(cr);
@@ -493,6 +498,7 @@ zpl_xattr_set(struct inode *ip, const char *name, const void *value,
crhold(cr);
cookie = spl_fstrans_mark();
+ rrm_enter_read(&(zsb)->z_teardown_lock, FTAG);
rw_enter(&ITOZ(ip)->z_xattr_lock, RW_WRITER);
/*
@@ -530,6 +536,7 @@ zpl_xattr_set(struct inode *ip, const char *name, const void *value,
error = zpl_xattr_set_dir(ip, name, value, size, flags, cr);
out:
rw_exit(&ITOZ(ip)->z_xattr_lock);
+ rrm_exit(&(zsb)->z_teardown_lock, FTAG);
spl_fstrans_unmark(cookie);
crfree(cr);
ASSERT3S(error, <=, 0);