Made bindfs mounts work with files opened with O_DIRECT

1 files changed, 40 insertions, 2 deletions

diff --git a/src/bindfs.c b/src/bindfs.c
index 332aa74..fff3a16 100644
--- a/src/bindfs.c
+++ b/src/bindfs.c
@@ -72,6 +72,9 @@
 #include <sys/xattr.h>
 #endif
 
+#include <sys/mman.h>
+#include <fcntl.h>
+
 #ifdef __LINUX__
 #include <linux/fs.h>  // For BLKGETSIZE64
 #endif
@@ -96,6 +99,10 @@
 #define XATTR_APPLE_PREFIX   "com.apple."
 #endif
 
+#ifndef O_DIRECT
+#define O_DIRECT 00040000 /* direct disk access hint */
+#endif
+
 /* We pessimistically assume signed uid_t and gid_t in our overflow checks,
    mostly because supporting both cases would require a bunch more code. */
 static const uid_t UID_T_MAX = ((1LL << (sizeof(uid_t)*8-1)) - 1);
@@ -1098,14 +1105,30 @@ static int bindfs_read(const char *path, char *buf, size_t size, off_t offset,
     int res;
     (void) path;
 
+    char * target_buf = buf;
+
     if (settings.read_limiter) {
         rate_limiter_wait(settings.read_limiter, size);
     }
 
-    res = pread(fi->fh, buf, size, offset);
+    unsigned int page_size = sysconf(_SC_PAGESIZE);
+    if (fi->flags & O_DIRECT) {
+        // allocate 512 bytes aligned buffer for direct io to work
+        target_buf = mmap(NULL, ((page_size - 1 + size) / page_size) * page_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+        if (target_buf == MAP_FAILED) {
+            return -ENOMEM;
+        }
+    }
+
+    res = pread(fi->fh, target_buf, size, offset);
     if (res == -1)
         res = -errno;
 
+    if (target_buf != buf) {
+        memcpy(buf, target_buf, size);
+        munmap(target_buf, ((page_size - 1 + size) / page_size) * page_size);
+    }
+
     return res;
 }
 
@@ -1114,15 +1137,30 @@ static int bindfs_write(const char *path, const char *buf, size_t size,
 {
     int res;
     (void) path;
+    char * source_buf = buf;
 
     if (settings.write_limiter) {
         rate_limiter_wait(settings.write_limiter, size);
     }
 
-    res = pwrite(fi->fh, buf, size, offset);
+    unsigned int page_size = sysconf(_SC_PAGESIZE);
+    if (fi->flags & O_DIRECT) {
+        // allocate 512 bytes aligned buffer for direct io to work
+        source_buf = mmap(NULL, ((page_size - 1 + size) / page_size) * page_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+        if (source_buf == MAP_FAILED) {
+            return -ENOMEM;
+        }
+        memcpy(source_buf, buf, size);
+    }
+
+    res = pwrite(fi->fh, source_buf, size, offset);
     if (res == -1)
         res = -errno;
 
+    if (source_buf != buf) {   
+        munmap(source_buf, ((page_size - 1 + size) / page_size) * page_size);
+    } 
+
     return res;
 }