[PATCH 05/11] fs, nfs: convert pnfs_layout_segment.pls_refcount from atomic_t to refcount_t

[Elena Reshetova]

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
 fs/nfs/pnfs.c | 12 ++++++------
 fs/nfs/pnfs.h |  4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 3bcd669..499bb71 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -450,7 +450,7 @@ pnfs_init_lseg(struct pnfs_layout_hdr *lo, struct 
pnfs_layout_segment *lseg,
 {
        INIT_LIST_HEAD(&lseg->pls_list);
        INIT_LIST_HEAD(&lseg->pls_lc_list);
-       atomic_set(&lseg->pls_refcount, 1);
+       refcount_set(&lseg->pls_refcount, 1);
        set_bit(NFS_LSEG_VALID, &lseg->pls_flags);
        lseg->pls_layout = lo;
        lseg->pls_range = *range;
@@ -507,13 +507,13 @@ pnfs_put_lseg(struct pnfs_layout_segment *lseg)
                return;
 
        dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
-               atomic_read(&lseg->pls_refcount),
+               refcount_read(&lseg->pls_refcount),
                test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
 
        lo = lseg->pls_layout;
        inode = lo->plh_inode;
 
-       if (atomic_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
+       if (refcount_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
                if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
                        spin_unlock(&inode->i_lock);
                        return;
@@ -551,7 +551,7 @@ pnfs_lseg_range_contained(const struct pnfs_layout_range 
*l1,
 static bool pnfs_lseg_dec_and_remove_zero(struct pnfs_layout_segment *lseg,
                struct list_head *tmp_list)
 {
-       if (!atomic_dec_and_test(&lseg->pls_refcount))
+       if (!refcount_dec_and_test(&lseg->pls_refcount))
                return false;
        pnfs_layout_remove_lseg(lseg->pls_layout, lseg);
        list_add(&lseg->pls_list, tmp_list);
@@ -570,7 +570,7 @@ static int mark_lseg_invalid(struct pnfs_layout_segment 
*lseg,
                 * outstanding io is finished.
                 */
                dprintk("%s: lseg %p ref %d\n", __func__, lseg,
-                       atomic_read(&lseg->pls_refcount));
+                       refcount_read(&lseg->pls_refcount));
                if (pnfs_lseg_dec_and_remove_zero(lseg, tmp_list))
                        rv = 1;
        }
@@ -1546,7 +1546,7 @@ pnfs_find_lseg(struct pnfs_layout_hdr *lo,
        }
 
        dprintk("%s:Return lseg %p ref %d\n",
-               __func__, ret, ret ? atomic_read(&ret->pls_refcount) : 0);
+               __func__, ret, ret ? refcount_read(&ret->pls_refcount) : 0);
        return ret;
 }
 
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index cefa7da..f0e98e1 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -64,7 +64,7 @@ struct pnfs_layout_segment {
        struct list_head pls_list;
        struct list_head pls_lc_list;
        struct pnfs_layout_range pls_range;
-       atomic_t pls_refcount;
+       refcount_t pls_refcount;
        u32 pls_seq;
        unsigned long pls_flags;
        struct pnfs_layout_hdr *pls_layout;
@@ -394,7 +394,7 @@ static inline struct pnfs_layout_segment *
 pnfs_get_lseg(struct pnfs_layout_segment *lseg)
 {
        if (lseg) {
-               atomic_inc(&lseg->pls_refcount);
+               refcount_inc(&lseg->pls_refcount);
                smp_mb__after_atomic();
        }
        return lseg;
-- 
2.7.4