Extend commit module to help with NFS quotas.

Add "commit on eof" and "commit past eof" modes. Patch from David
Losada Carballo with some modifications during the merge.
(This used to be commit 12eee4f7fe27bb4ca376301b959dbfb918b7ba2d)

1 files changed, 158 insertions, 25 deletions

diff --git a/source3/modules/vfs_commit.c b/source3/modules/vfs_commit.c
index 39de7f7e74..d7d81924f1 100644
--- a/source3/modules/vfs_commit.c
+++ b/source3/modules/vfs_commit.c
@@ -1,5 +1,6 @@
 /*
- * Copyright (c) James Peach 2006
+ * Copyright (c) James Peach 2006, 2007
+ * Copyright (c) David Losada Carballo 2007
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -29,23 +30,73 @@
  * Tunables:
  *
  *  commit: dthresh         Amount of dirty data that can accumulate
- *			                before we commit (sync) it.
+ *                          before we commit (sync) it.
  *
  *  commit: debug           Debug level at which to emit messages.
  *
+ *  commit: eof mode        String. Tunes how the module tries to guess when
+ *                          the client has written the last bytes of the file.
+ *                          Possible values (default = hinted):
+ *
+ *     (*)  = hinted        Some clients (i.e. Windows Explorer) declare the
+ *                          size of the file before transferring it. With this
+ *                          option, we remember that hint, and commit after
+ *                          writing in that file position. If the client
+ *                          doesn't declare the size of file, commiting on EOF 
+ *                          is not triggered.
+ *
+ *          = growth        Commits after a write operation has made the file
+ *                          size grow. If the client declares a file size, it
+ *                          refrains to commit until the file has reached it.
+ *                          Useful for defeating writeback on NFS shares.
+ *
  */
 
 #define MODULE "commit"
 
 static int module_debug;
 
+enum eof_mode
+{
+    EOF_NONE = 0x0000,
+    EOF_HINTED = 0x0001,
+    EOF_GROWTH = 0x0002
+};
+
 struct commit_info
 {
+        /* For chunk-based commits */
         SMB_OFF_T dbytes;	/* Dirty (uncommitted) bytes */
         SMB_OFF_T dthresh;	/* Dirty data threshold */
+        /* For commits on EOF */
+        enum eof_mode on_eof;
+        SMB_OFF_T eof;		/* Expected file size */
 };
 
-static void commit_all(
+static int commit_do(
+        struct commit_info *            c,
+        int                             fd)
+{
+        int result;
+
+	DEBUG(module_debug,
+		("%s: flushing %lu dirty bytes\n",
+		 MODULE, (unsigned long)c->dbytes));
+
+#if HAVE_FDATASYNC
+        result = fdatasync(fd);
+#elif HAVE_FSYNC
+        result = fsync(fd);
+#else
+	result = 0
+#endif
+        if (result == 0) {
+                c->dbytes = 0;	/* on success, no dirty bytes */
+        }
+        return result;
+}
+
+static int commit_all(
         struct vfs_handle_struct *	handle,
         files_struct *		        fsp)
 {
@@ -57,34 +108,52 @@ static void commit_all(
                                 ("%s: flushing %lu dirty bytes\n",
                                  MODULE, (unsigned long)c->dbytes));
 
-                        fdatasync(fsp->fh->fd);
-                        c->dbytes = 0;
+                        return commit_do(c, fsp->fh->fd);
                 }
         }
+        return 0;
 }
 
-static void commit(
+static int commit(
         struct vfs_handle_struct *	handle,
         files_struct *		        fsp,
+	SMB_OFF_T			offset,
         ssize_t			        last_write)
 {
         struct commit_info *c;
 
-        if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
+        if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp)) == NULL) {
+		return 0;
+	}
 
-                if (last_write > 0) {
-                        c->dbytes += last_write;
-                }
+	c->dbytes += last_write;	/* dirty bytes always counted */
 
-                if (c->dbytes > c->dthresh) {
-                        DEBUG(module_debug,
-                                ("%s: flushing %lu dirty bytes\n",
-                                 MODULE, (unsigned long)c->dbytes));
+	if (c->dthresh && (c->dbytes > c->dthresh)) {
+		return commit_do(c, fsp->fh->fd);
+	}
 
-                        fdatasync(fsp->fh->fd);
-                        c->dbytes = 0;
-                }
-        }
+	/* Return if we are not in EOF mode or if we have temporarily opted
+	 * out of it.
+	 */
+	if (c->on_eof == EOF_NONE || c->eof < 0) {
+		return 0;
+	}
+
+	/* This write hit or went past our cache the file size. */
+	if ((offset + last_write) >= c->eof) {
+		if (commit_do(c, fsp->fh->fd) == -1) {
+			return -1;
+		}
+
+		/* Hinted mode only commits the first time we hit EOF. */
+		if (c->on_eof == EOF_HINTED) {
+		    c->eof = -1;
+		} else if (c->on_eof == EOF_GROWTH) {
+		    c->eof = offset + last_write;
+		}
+	}
+
+        return 0;
 }
 
 static int commit_connect(
@@ -104,25 +173,57 @@ static int commit_open(
 	mode_t		    mode)
 {
         SMB_OFF_T dthresh;
+	const char *eof_mode;
+        struct commit_info *c = NULL;
+        int fd;
 
         /* Don't bother with read-only files. */
         if ((flags & O_ACCMODE) == O_RDONLY) {
                 return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
         }
 
+        /* Read and check module configuration */
         dthresh = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
                                         MODULE, "dthresh", NULL));
 
-        if (dthresh > 0) {
-                struct commit_info * c;
+	eof_mode = lp_parm_const_string(SNUM(handle->conn),
+                                        MODULE, "eof mode", "none");
+
+        if (dthresh > 0 || !strequal(eof_mode, "none")) {
                 c = VFS_ADD_FSP_EXTENSION(handle, fsp, struct commit_info);
+                /* Process main tunables */
                 if (c) {
                         c->dthresh = dthresh;
                         c->dbytes = 0;
+                        c->on_eof = EOF_NONE;
+                        c->eof = 0;
+                }
+        }
+        /* Process eof_mode tunable */
+        if (c) {
+                if (strequal(eof_mode, "hinted")) {
+                        c->on_eof = EOF_HINTED;
+                } else if (strequal(eof_mode, "growth")) {
+                        c->on_eof = EOF_GROWTH;
+                }
+        }
+
+        fd = SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
+	if (fd == -1) {
+		VFS_REMOVE_FSP_EXTENSION(handle, fsp);
+		return fd;
+	}
+
+        /* EOF commit modes require us to know the initial file size. */
+        if (c && (c->on_eof != EOF_NONE)) {
+                SMB_STRUCT_STAT st;
+                if (SMB_VFS_FSTAT(fsp, fd, &st) == -1) {
+                        return -1;
                 }
+		c->eof = st.st_size;
         }
 
-        return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
+        return 0;
 }
 
 static ssize_t commit_write(
@@ -133,9 +234,13 @@ static ssize_t commit_write(
         size_t              count)
 {
         ssize_t ret;
-
         ret = SMB_VFS_NEXT_WRITE(handle, fsp, fd, data, count);
-        commit(handle, fsp, ret);
+
+        if (ret > 0) {
+                if (commit(handle, fsp, fsp->fh->pos, ret) == -1) {
+                        return -1;
+                }
+        }
 
         return ret;
 }
@@ -151,20 +256,45 @@ static ssize_t commit_pwrite(
         ssize_t ret;
 
         ret = SMB_VFS_NEXT_PWRITE(handle, fsp, fd, data, count, offset);
-        commit(handle, fsp, ret);
+        if (ret > 0) {
+                if (commit(handle, fsp, offset, ret) == -1) {
+                        return -1;
+                }
+        }
 
         return ret;
 }
 
-static ssize_t commit_close(
+static int commit_close(
         vfs_handle_struct * handle,
         files_struct *      fsp,
         int                 fd)
 {
+        /* Commit errors not checked, close() will find them again */
         commit_all(handle, fsp);
         return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
 }
 
+static int commit_ftruncate(
+        vfs_handle_struct * handle,
+        files_struct *      fsp,
+        int                 fd,
+        SMB_OFF_T           len)
+{
+        int result;
+
+        result = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, fd, len);
+        if (result == 0) {
+		struct commit_info *c;
+		if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
+			commit(handle, fsp, len, 0);
+			c->eof = len;
+		}
+        }
+
+        return result;
+}
+
 static vfs_op_tuple commit_ops [] =
 {
         {SMB_VFS_OP(commit_open),
@@ -177,6 +307,8 @@ static vfs_op_tuple commit_ops [] =
                 SMB_VFS_OP_PWRITE, SMB_VFS_LAYER_TRANSPARENT},
         {SMB_VFS_OP(commit_connect),
                 SMB_VFS_OP_CONNECT,  SMB_VFS_LAYER_TRANSPARENT},
+        {SMB_VFS_OP(commit_ftruncate),
+                SMB_VFS_OP_FTRUNCATE,  SMB_VFS_LAYER_TRANSPARENT},
 
         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 };
@@ -187,3 +319,4 @@ NTSTATUS vfs_commit_init(void)
 	return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, MODULE, commit_ops);
 }
 
+