Commit 4a30131e authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
Browse files

[PATCH] Fix some problems with truncate and mtime semantics. 



SUS requires that when truncating a file to the size that it currently
is:
  truncate and ftruncate should NOT modify ctime or mtime
  O_TRUNC SHOULD modify ctime and mtime.

Currently mtime and ctime are always modified on most local
filesystems (side effect of ->truncate) or never modified (on NFS).

With this patch:
  ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when
    an update of these times is required whether size changes or not
    (via a new argument to do_truncate).  This allows NFS to do
    the right thing for O_TRUNC.
  inode_setattr nolonger forces ATTR_MTIME|ATTR_CTIME when the ATTR_SIZE
    sets the size to it's current value.  This allows local filesystems
    to do the right thing for f?truncate.

Also, the logic in inode_setattr is changed a bit so there are two return
points.  One returns the error from vmtruncate if it failed, the other
returns 0 (there can be no other failure).

Finally, if vmtruncate succeeds, and ATTR_SIZE is the only change
requested, we now fall-through and mark_inode_dirty.  If a filesystem did
not have a ->truncate function, then vmtruncate will have changed i_size,
without marking the inode as 'dirty', and I think this is wrong.

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 78854014

fs/attr.c

+8 −16
Original line number Diff line number Diff line
@@ -67,20 +67,12 @@ EXPORT_SYMBOL(inode_change_ok); 
int inode_setattr(struct inode * inode, struct iattr * attr)

{

	unsigned int ia_valid = attr->ia_valid;

	int error = 0;



	if (ia_valid & ATTR_SIZE) {

		if (attr->ia_size != i_size_read(inode)) {

			error = vmtruncate(inode, attr->ia_size);

			if (error || (ia_valid == ATTR_SIZE))

				goto out;

		} else {

			/*

			 * We skipped the truncate but must still update

			 * timestamps

			 */

			ia_valid |= ATTR_MTIME|ATTR_CTIME;

		}

	if (ia_valid & ATTR_SIZE &&

	    attr->ia_size != i_size_read(inode)) {

		int error = vmtruncate(inode, attr->ia_size);

		if (error)

			return error;

	}



	if (ia_valid & ATTR_UID)
@@ -104,8 +96,8 @@ int inode_setattr(struct inode * inode, struct iattr * attr) 
		inode->i_mode = mode;

	}

	mark_inode_dirty(inode);

out:

	return error;



	return 0;

}

EXPORT_SYMBOL(inode_setattr);

fs/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -1505,7 +1505,7 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) 
		goto close_fail;

	if (!file->f_op->write)

		goto close_fail;

	if (do_truncate(file->f_dentry, 0, file) != 0)

	if (do_truncate(file->f_dentry, 0, 0, file) != 0)

		goto close_fail;



	retval = binfmt->core_dump(signr, regs, file);

fs/namei.c

+1 −1
Original line number Diff line number Diff line
@@ -1491,7 +1491,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) 
		if (!error) {

			DQUOT_INIT(inode);

			

			error = do_truncate(dentry, 0, NULL);

			error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, NULL);

		}

		put_write_access(inode);

		if (error)

fs/open.c

+5 −4
Original line number Diff line number Diff line
@@ -194,7 +194,8 @@ out: 
	return error;

}



int do_truncate(struct dentry *dentry, loff_t length, struct file *filp)

int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,

	struct file *filp)

{

	int err;

	struct iattr newattrs;
@@ -204,7 +205,7 @@ int do_truncate(struct dentry *dentry, loff_t length, struct file *filp) 
		return -EINVAL;



	newattrs.ia_size = length;

	newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;

	newattrs.ia_valid = ATTR_SIZE | time_attrs;

	if (filp) {

		newattrs.ia_file = filp;

		newattrs.ia_valid |= ATTR_FILE;
@@ -266,7 +267,7 @@ static inline long do_sys_truncate(const char __user * path, loff_t length) 
	error = locks_verify_truncate(inode, NULL, length);

	if (!error) {

		DQUOT_INIT(inode);

		error = do_truncate(nd.dentry, length, NULL);

		error = do_truncate(nd.dentry, length, 0, NULL);

	}

	put_write_access(inode);
@@ -318,7 +319,7 @@ static inline long do_sys_ftruncate(unsigned int fd, loff_t length, int small) 


	error = locks_verify_truncate(inode, file, length);

	if (!error)

		error = do_truncate(dentry, length, file);

		error = do_truncate(dentry, length, 0, file);

out_putf:

	fput(file);

out:

include/linux/fs.h

+2 −1
Original line number Diff line number Diff line
@@ -1344,7 +1344,8 @@ static inline int break_lease(struct inode *inode, unsigned int mode) 


/* fs/open.c */



extern int do_truncate(struct dentry *, loff_t start, struct file *filp);

extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,

		       struct file *filp);

extern long do_sys_open(const char __user *filename, int flags, int mode);

extern struct file *filp_open(const char *, int, int);

extern struct file * dentry_open(struct dentry *, struct vfsmount *, int);

CRA Git | Maintained and supported by SUSTech CRA and CCSE