From: Darrick J. Wong <[email protected]> d_tmpfile was introduced to instantiate an inode in the dentry cache as a temporary file. This helper decrements the inode's nlink count and dirties the inode, presumably so that filesystems could call new_inode to create a new inode with nlink == 1 and then call d_tmpfile which will decrement nlink.
However, this doesn't play well with XFS, which needs to allocate, initialize, and insert a tempfile inode on its unlinked list in a single transaction. In order to maintain referential integrity of the XFS metadata, we cannot have an inode on the unlinked list with nlink >= 1. XFS and btrfs hack around d_tmpfile's behavior by creating the inode with nlink == 0 and then incrementing it just prior to calling d_tmpfile, anticipating that it will be reset to 0. Everywhere else, it appears that nlink updates and persistence is the responsibility of individual filesystems. Therefore, move the nlink decrement out of d_tmpfile into the callers, and require that callers only pass in inodes with nlink already set to 0. Signed-off-by: Darrick J. Wong <[email protected]> --- v2: convert BUG_ON to WARN_ON per review comment --- fs/btrfs/inode.c | 8 -------- fs/dcache.c | 10 ++++++---- fs/ext2/namei.c | 2 +- fs/ext4/namei.c | 1 + fs/f2fs/namei.c | 1 + fs/minix/namei.c | 2 +- fs/ubifs/dir.c | 1 + fs/udf/namei.c | 2 +- fs/xfs/xfs_iops.c | 13 ++----------- mm/shmem.c | 1 + 10 files changed, 15 insertions(+), 26 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 5c349667c761..bd189fc50f83 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -10382,14 +10382,6 @@ static int btrfs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) if (ret) goto out; - /* - * We set number of links to 0 in btrfs_new_inode(), and here we set - * it to 1 because d_tmpfile() will issue a warning if the count is 0, - * through: - * - * d_tmpfile() -> inode_dec_link_count() -> drop_nlink() - */ - set_nlink(inode, 1); d_tmpfile(dentry, inode); unlock_new_inode(inode); mark_inode_dirty(inode); diff --git a/fs/dcache.c b/fs/dcache.c index aac41adf4743..bb349d423055 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -3042,12 +3042,14 @@ void d_genocide(struct dentry *parent) EXPORT_SYMBOL(d_genocide); +/* + * Instantiate an inode in the dentry cache as a temporary file. Callers must + * ensure that @inode has a zero link count. + */ void d_tmpfile(struct dentry *dentry, struct inode *inode) { - inode_dec_link_count(inode); - BUG_ON(dentry->d_name.name != dentry->d_iname || - !hlist_unhashed(&dentry->d_u.d_alias) || - !d_unlinked(dentry)); + WARN_ON(dentry->d_name.name != dentry->d_iname || + !d_unlinked(dentry) || inode->i_nlink != 0); spin_lock(&dentry->d_parent->d_lock); spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c index 0c26dcc5d850..8542e9ce9677 100644 --- a/fs/ext2/namei.c +++ b/fs/ext2/namei.c @@ -117,7 +117,7 @@ static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) return PTR_ERR(inode); ext2_set_file_ops(inode); - mark_inode_dirty(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); unlock_new_inode(inode); return 0; diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 2b928eb07fa2..7502432f9816 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2517,6 +2517,7 @@ static int ext4_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) inode->i_op = &ext4_file_inode_operations; inode->i_fop = &ext4_file_operations; ext4_set_aops(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); err = ext4_orphan_add(handle, inode); if (err) diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c index 62d9829f3a6a..31a556af5f3a 100644 --- a/fs/f2fs/namei.c +++ b/fs/f2fs/namei.c @@ -780,6 +780,7 @@ static int __f2fs_tmpfile(struct inode *dir, struct dentry *dentry, f2fs_i_links_write(inode, false); *whiteout = inode; } else { + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } /* link_count was changed by d_tmpfile as well. */ diff --git a/fs/minix/namei.c b/fs/minix/namei.c index 1a6084d2b02e..3249f86c476a 100644 --- a/fs/minix/namei.c +++ b/fs/minix/namei.c @@ -57,7 +57,7 @@ static int minix_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) struct inode *inode = minix_new_inode(dir, mode, &error); if (inode) { minix_set_inode(inode, 0); - mark_inode_dirty(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } return error; diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index 5767b373a8ff..7187e4fd7561 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -419,6 +419,7 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry, drop_nlink(inode); *whiteout = inode; } else { + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } ubifs_assert(c, ui->dirty); diff --git a/fs/udf/namei.c b/fs/udf/namei.c index 58cc2414992b..38bd021f9673 100644 --- a/fs/udf/namei.c +++ b/fs/udf/namei.c @@ -652,7 +652,7 @@ static int udf_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) inode->i_data.a_ops = &udf_aops; inode->i_op = &udf_file_inode_operations; inode->i_fop = &udf_file_operations; - mark_inode_dirty(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); unlock_new_inode(inode); return 0; diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index 1efef69a7f1c..f48ffd7a8d3e 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -191,18 +191,9 @@ xfs_generic_create( xfs_setup_iops(ip); - if (tmpfile) { - /* - * The VFS requires that any inode fed to d_tmpfile must have - * nlink == 1 so that it can decrement the nlink in d_tmpfile. - * However, we created the temp file with nlink == 0 because - * we're not allowed to put an inode with nlink > 0 on the - * unlinked list. Therefore we have to set nlink to 1 so that - * d_tmpfile can immediately set it back to zero. - */ - set_nlink(inode, 1); + if (tmpfile) d_tmpfile(dentry, inode); - } else + else d_instantiate(dentry, inode); xfs_finish_inode_setup(ip); diff --git a/mm/shmem.c b/mm/shmem.c index 6ece1e2fe76e..4a7810093561 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2818,6 +2818,7 @@ shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) error = simple_acl_create(dir, inode); if (error) goto out_iput; + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } return error; _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
