Large block sizes on Linux are now ignored (ticket #1168). NFS on Linux is known to report wsize as a block size (in both f_bsize and f_frsize, both in statfs() and statvfs()). On the other hand, typical file system block sizes on Linux (ext2/ext3/ext4, XFS) are limited to pagesize. (With FAT, block sizes can be at least up to 512k in extreme cases, but this doesn't really matter, see below.) To avoid too aggressive cache clearing on NFS volumes on Linux, block sizes larger than pagesize are now ignored. Note that it is safe to ignore large block sizes. Since 3899:e7cd13b7f759 (1.0.1) cache size is calculated based on fstat() st_blocks, and rounding to file system block size is preserved mostly for Windows. Note well that on other OSes valid block sizes seen are at least up to 65536. In particular, UFS on FreeBSD is known to work well with block and fragment sizes set to 65536.

--- a/src/os/unix/ngx_files.c
+++ b/src/os/unix/ngx_files.c
@@ -875,6 +875,12 @@ ngx_fs_bsize(u_char *name)
         return 512;
     }
 
+#if (NGX_LINUX)
+    if ((size_t) fs.f_bsize > ngx_pagesize) {
+        return 512;
+    }
+#endif
+
     return (size_t) fs.f_bsize;
 }
 
@@ -893,6 +899,12 @@ ngx_fs_bsize(u_char *name)
         return 512;
     }
 
+#if (NGX_LINUX)
+    if ((size_t) fs.f_frsize > ngx_pagesize) {
+        return 512;
+    }
+#endif
+
     return (size_t) fs.f_frsize;
 }