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From: Dave Hansen <haveblue@us.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: hch@lst.de, viro@ZenIV.linux.org.uk, viro@ftp.linux.org.uk,
	miklos@szeredi.hu, Dave Hansen <haveblue@us.ibm.com>
Subject: [RFC][PATCH 05/30] do namei_flags calculation inside open_namei()
Date: Fri, 08 Feb 2008 14:26:53 -0800	[thread overview]
Message-ID: <20080208222652.DDF5F2A0@kernel> (raw)
In-Reply-To: <20080208222641.6024A7CC@kernel>


My end goal here is to make sure all users of may_open()
return filps.  This will ensure that we properly release
mount write counts which were taken for the filp in
may_open().

This patch moves the sys_open flags to namei flags
calculation into fs/namei.c.  We'll shortly be moving
the nameidata_to_filp() calls into namei.c, and this
gets the sys_open flags to a place where we can get
at them when we need them.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

 linux-2.6.git-dave/fs/namei.c |   43 +++++++++++++++++++++++++++++++++---------
 linux-2.6.git-dave/fs/open.c  |   22 +--------------------
 2 files changed, 36 insertions(+), 29 deletions(-)

diff -puN fs/namei.c~do-namei_flags-calculation-inside-open_namei fs/namei.c
--- linux-2.6.git/fs/namei.c~do-namei_flags-calculation-inside-open_namei	2008-02-08 13:04:46.000000000 -0800
+++ linux-2.6.git-dave/fs/namei.c	2008-02-08 13:04:46.000000000 -0800
@@ -1674,7 +1674,12 @@ int may_open(struct nameidata *nd, int a
 	return 0;
 }
 
-static int open_namei_create(struct nameidata *nd, struct path *path,
+/*
+ * Be careful about ever adding any more callers of this
+ * function.  Its flags must be in the namei format, not
+ * what get passed to sys_open().
+ */
+static int __open_namei_create(struct nameidata *nd, struct path *path,
 				int flag, int mode)
 {
 	int error;
@@ -1693,26 +1698,46 @@ static int open_namei_create(struct name
 }
 
 /*
+ * Note that while the flag value (low two bits) for sys_open means:
+ *	00 - read-only
+ *	01 - write-only
+ *	10 - read-write
+ *	11 - special
+ * it is changed into
+ *	00 - no permissions needed
+ *	01 - read-permission
+ *	10 - write-permission
+ *	11 - read-write
+ * for the internal routines (ie open_namei()/follow_link() etc)
+ * This is more logical, and also allows the 00 "no perm needed"
+ * to be used for symlinks (where the permissions are checked
+ * later).
+ *
+*/
+static inline int open_to_namei_flags(int flag)
+{
+	if ((flag+1) & O_ACCMODE)
+		flag++;
+	return flag;
+}
+
+/*
  *	open_namei()
  *
  * namei for open - this is in fact almost the whole open-routine.
  *
  * Note that the low bits of "flag" aren't the same as in the open
- * system call - they are 00 - no permissions needed
- *			  01 - read permission needed
- *			  10 - write permission needed
- *			  11 - read/write permissions needed
- * which is a lot more logical, and also allows the "no perm" needed
- * for symlinks (where the permissions are checked later).
+ * system call.  See open_to_namei_flags().
  * SMP-safe
  */
-int open_namei(int dfd, const char *pathname, int flag,
+int open_namei(int dfd, const char *pathname, int open_flag,
 		int mode, struct nameidata *nd)
 {
 	int acc_mode, error;
 	struct path path;
 	struct dentry *dir;
 	int count = 0;
+	int flag = open_to_namei_flags(open_flag);
 
 	acc_mode = ACC_MODE(flag);
 
@@ -1773,7 +1798,7 @@ do_last:
 
 	/* Negative dentry, just create the file */
 	if (!path.dentry->d_inode) {
-		error = open_namei_create(nd, &path, flag, mode);
+		error = __open_namei_create(nd, &path, flag, mode);
 		if (error)
 			goto exit;
 		return 0;
diff -puN fs/open.c~do-namei_flags-calculation-inside-open_namei fs/open.c
--- linux-2.6.git/fs/open.c~do-namei_flags-calculation-inside-open_namei	2008-02-08 13:04:46.000000000 -0800
+++ linux-2.6.git-dave/fs/open.c	2008-02-08 13:04:46.000000000 -0800
@@ -800,31 +800,13 @@ cleanup_file:
 	return ERR_PTR(error);
 }
 
-/*
- * Note that while the flag value (low two bits) for sys_open means:
- *	00 - read-only
- *	01 - write-only
- *	10 - read-write
- *	11 - special
- * it is changed into
- *	00 - no permissions needed
- *	01 - read-permission
- *	10 - write-permission
- *	11 - read-write
- * for the internal routines (ie open_namei()/follow_link() etc). 00 is
- * used by symlinks.
- */
 static struct file *do_filp_open(int dfd, const char *filename, int flags,
 				 int mode)
 {
-	int namei_flags, error;
+	int error;
 	struct nameidata nd;
 
-	namei_flags = flags;
-	if ((namei_flags+1) & O_ACCMODE)
-		namei_flags++;
-
-	error = open_namei(dfd, filename, namei_flags, mode, &nd);
+	error = open_namei(dfd, filename, flags, mode, &nd);
 	if (!error)
 		return nameidata_to_filp(&nd, flags);
 
_

  parent reply	other threads:[~2008-02-08 22:29 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-08 22:26 [RFC][PATCH 00/30] Read-only bind mounts (-mm resend) Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 01/30] reiserfs: eliminate private use of struct file in xattr Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 02/30] hppfs pass vfsmount to dentry_open() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 03/30] check for null vfsmount in dentry_open() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 04/30] fix up new filp allocators Dave Hansen
2008-02-08 22:26 ` Dave Hansen [this message]
2008-02-08 22:26 ` [RFC][PATCH 06/30] make open_namei() return a filp Dave Hansen
2008-02-09  5:09   ` Christoph Hellwig
2008-02-08 22:26 ` [RFC][PATCH 07/30] r/o bind mounts: stub functions Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 08/30] r/o bind mounts: create helper to drop file write access Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 09/30] r/o bind mounts: drop write during emergency remount Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 10/30] r/o bind mounts: elevate write count for vfs_rmdir() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 11/30] r/o bind mounts: elevate write count for callers of vfs_mkdir() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 12/30] r/o bind mounts: elevate mnt_writers for unlink callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 13/30] r/o bind mounts: elevate write count for xattr_permission() callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 14/30] r/o bind mounts: elevate write count for ncp_ioctl() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 15/30] r/o bind mounts: write counts for time functions Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 16/30] r/o bind mounts: elevate write count for do_utimes() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 17/30] r/o bind mounts: write count for file_update_time() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 18/30] r/o bind mounts: write counts for link/symlink Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 19/30] r/o bind mounts: elevate write count for ioctls() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 20/30] r/o bind mounts: elevate write count for open()s Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 21/30] r/o bind mounts: get write access for vfs_rename() callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 22/30] r/o bind mounts: elevate write count for chmod/chown callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 23/30] r/o bind mounts: write counts for truncate() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 24/30] r/o bind mounts: elevate count for xfs timestamp updates Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 25/30] r/o bind mounts: make access() use new r/o helper Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 26/30] r/o bind mounts: check mnt instead of superblock directly Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 27/30] r/o bind mounts: get callers of vfs_mknod/create() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 28/30] r/o bind mounts: track numbers of writers to mounts Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 29/30] r/o bind mounts: honor mount writer counts at remount Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 30/30] r/o bind mounts: debugging for missed calls Dave Hansen
2008-02-09  6:39 ` [RFC][PATCH 00/30] Read-only bind mounts (-mm resend) Christoph Hellwig
2008-02-09  7:57 ` Al Viro
2008-02-12  5:06 ` Christoph Hellwig

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