From: Miklos Szeredi Date: Thu, 18 Oct 2007 10:07:00 +0000 (-0700) Subject: VFS: allow filesystems to implement atomic open+truncate X-Git-Tag: v3.12-rc1~25331 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d139d7ffd0c1e81e2a809909b4f8b121a0dc119a;p=kernel%2Fkernel-generic.git VFS: allow filesystems to implement atomic open+truncate Add a new attribute flag ATTR_OPEN, with the meaning: "truncation was initiated by open() due to the O_TRUNC flag". This way filesystems wanting to implement truncation within their ->open() method can ignore such truncate requests. This is a quick & dirty hack, but it comes for free. Signed-off-by: Miklos Szeredi Cc: Christoph Hellwig Cc: Al Viro Cc: Andreas Dilger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/namei.c b/fs/namei.c index 464eecc..1e5c716 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1659,8 +1659,10 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) error = locks_verify_locked(inode); if (!error) { DQUOT_INIT(inode); - - error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, NULL); + + error = do_truncate(dentry, 0, + ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, + NULL); } put_write_access(inode); if (error) diff --git a/include/linux/fs.h b/include/linux/fs.h index e3fc5db..6a4d170 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -330,6 +330,7 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset, #define ATTR_KILL_SGID 4096 #define ATTR_FILE 8192 #define ATTR_KILL_PRIV 16384 +#define ATTR_OPEN 32768 /* Truncating from open(O_TRUNC) */ /* * This is the Inode Attributes structure, used for notify_change(). It