fs/ntfs3: Fix multithreaded stress test

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

diff --git a/fs/ntfs3/attrib.c b/fs/ntfs3/attrib.c
index 63f70259edc0d44d6a52c946c9a90663fe16722a..4b78b669a3bdb3a92ad479335b7508f093fdb305 100644 (file)
--- a/fs/ntfs3/attrib.c
+++ b/fs/ntfs3/attrib.c
@@ -886,7 +886,7 @@ int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
        struct runs_tree *run = &ni->file.run;
        struct ntfs_sb_info *sbi;
        u8 cluster_bits;
-       struct ATTRIB *attr = NULL, *attr_b;
+       struct ATTRIB *attr, *attr_b;
        struct ATTR_LIST_ENTRY *le, *le_b;
        struct mft_inode *mi, *mi_b;
        CLST hint, svcn, to_alloc, evcn1, next_svcn, asize, end, vcn0, alen;
@@ -904,12 +904,8 @@ int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
                *len = 0;
        up_read(&ni->file.run_lock);
 
-       if (*len) {
-               if (*lcn != SPARSE_LCN || !new)
-                       return 0; /* Fast normal way without allocation. */
-               else if (clen > *len)
-                       clen = *len;
-       }
+       if (*len && (*lcn != SPARSE_LCN || !new))
+               return 0; /* Fast normal way without allocation. */
 
        /* No cluster in cache or we need to allocate cluster in hole. */
        sbi = ni->mi.sbi;
@@ -918,6 +914,17 @@ int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
        ni_lock(ni);
        down_write(&ni->file.run_lock);
 
+       /* Repeat the code above (under write lock). */
+       if (!run_lookup_entry(run, vcn, lcn, len, NULL))
+               *len = 0;
+
+       if (*len) {
+               if (*lcn != SPARSE_LCN || !new)
+                       goto out; /* normal way without allocation. */
+               if (clen > *len)
+                       clen = *len;
+       }
+
        le_b = NULL;
        attr_b = ni_find_attr(ni, NULL, &le_b, ATTR_DATA, NULL, 0, NULL, &mi_b);
        if (!attr_b) {