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

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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: Neil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown
2006-01-08 01:02:39 -08:00
committed by Linus Torvalds
parent 788540141f
commit 4a30131e7d
5 changed files with 16 additions and 22 deletions
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9
fs/open.c
View File

@@ -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: