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Commit d139d7ff authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds
Browse files

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: default avatarMiklos Szeredi <mszeredi@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 49d4914f

fs/namei.c

+4 −2
Original line number Diff line number Diff line
@@ -1660,7 +1660,9 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) 
		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)

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -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