Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes:
> On Thu, Oct 23, 2014 at 05:55:33PM +0100, Al Viro wrote:
>> On Fri, Oct 24, 2014 at 01:45:49AM +0900, OGAWA Hirofumi wrote:
>>
>> > d_splice_alias() calls __d_find_alias() with want_discon==1, so
>> > __d_find_alias() doesn't return dentry, and d_splice_alias() doesn't use
>> > d_move() path, right?
>>
>> Hmm... Not in the current mainline (and not because of want_discon - that's
>> gone already). However, with the fixes I've got in the local tree it
>> will both find and move it - same as d_materialise_unique() would in the
>> current mainline.
>
> Untested interim fix follows; as soon as d_splice_alias()/d_materialise_unique()
> merge happens, we'll be able to clean vfat_lookup() a bit more.
>
> a) don't bother with ->d_time for positives - we only check it for negatives
> anyway.
> b) make sure to set it at unlink and rmdir time - at *that* point soon-to-be
> negative dentry matches then-current directory contents
> c) don't go into renaming of old alias in vfat_lookup() unless it has
> the same parent (which it will, unless we are seeing corrupted image) *and*
> is a non-directory
> d) use (for now) d_materialise_unique() instead of d_splice_alias() - that one
> will do renames of old directory aliases just fine (and pretty soon so will
> d_splice_alias(), but this bug is -stable fodder)
Ah, this calls d_move() for directory?
I recalled why it didn't change alias if directory. Changing result of
getcwd() may become the surprise of apps... If doesn't surprise, looks
good.
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
> diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
> index 6df8d3d..eed856f 100644
> --- a/fs/fat/namei_vfat.c
> +++ b/fs/fat/namei_vfat.c
> @@ -736,17 +736,17 @@ static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
> }
>
> alias = d_find_alias(inode);
> - if (alias && !vfat_d_anon_disconn(alias)) {
> + if (alias && alias->d_parent == dentry->d_parent &&
> + !S_ISDIR(inode->i_mode) && !vfat_d_anon_disconn(alias)) {
> /*
> - * This inode has non anonymous-DCACHE_DISCONNECTED
> + * This file has non anonymous-DCACHE_DISCONNECTED
> * dentry. This means, the user did ->lookup() by an
> * another name (longname vs 8.3 alias of it) in past.
> *
> * Switch to new one for reason of locality if possible.
> */
> BUG_ON(d_unhashed(alias));
> - if (!S_ISDIR(inode->i_mode))
> - d_move(alias, dentry);
> + d_move(alias, dentry);
> iput(inode);
> mutex_unlock(&MSDOS_SB(sb)->s_lock);
> return alias;
> @@ -755,12 +755,9 @@ static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
>
> out:
> mutex_unlock(&MSDOS_SB(sb)->s_lock);
> - dentry->d_time = dentry->d_parent->d_inode->i_version;
> - dentry = d_splice_alias(inode, dentry);
> - if (dentry)
> - dentry->d_time = dentry->d_parent->d_inode->i_version;
> - return dentry;
> -
> + if (!inode)
> + dentry->d_time = dir->i_version;
> + return d_materialise_unique(dentry, inode);
> error:
> mutex_unlock(&MSDOS_SB(sb)->s_lock);
> return ERR_PTR(err);
> @@ -793,7 +790,6 @@ static int vfat_create(struct inode *dir, struct dentry *dentry, umode_t mode,
> inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
> /* timestamp is already written, so mark_inode_dirty() is unneeded. */
>
> - dentry->d_time = dentry->d_parent->d_inode->i_version;
> d_instantiate(dentry, inode);
> out:
> mutex_unlock(&MSDOS_SB(sb)->s_lock);
> @@ -824,6 +820,7 @@ static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
> clear_nlink(inode);
> inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
> fat_detach(inode);
> + dentry->d_time = dir->i_version;
> out:
> mutex_unlock(&MSDOS_SB(sb)->s_lock);
>
> @@ -849,6 +846,7 @@ static int vfat_unlink(struct inode *dir, struct dentry *dentry)
> clear_nlink(inode);
> inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
> fat_detach(inode);
> + dentry->d_time = dir->i_version;
> out:
> mutex_unlock(&MSDOS_SB(sb)->s_lock);
>
> @@ -889,7 +887,6 @@ static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
> inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
> /* timestamp is already written, so mark_inode_dirty() is unneeded. */
>
> - dentry->d_time = dentry->d_parent->d_inode->i_version;
> d_instantiate(dentry, inode);
>
> mutex_unlock(&MSDOS_SB(sb)->s_lock);
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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