Commit 4a30131e authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] Fix some problems with truncate and mtime semantics.

SUS requires that when truncating a file to the size that it currently
  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 <>
Cc: Christoph Hellwig <>
Cc: Trond Myklebust <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 78854014
......@@ -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
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;
return error;
return 0;
......@@ -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);
......@@ -1491,7 +1491,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
if (!error) {
error = do_truncate(dentry, 0, NULL);
error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, NULL);
if (error)
......@@ -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) {
error = do_truncate(nd.dentry, length, NULL);
error = do_truncate(nd.dentry, length, 0, NULL);
......@@ -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);
......@@ -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);
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