UBIFS: optimize deletions

Every time anything is deleted, UBIFS writes the deletion inode
node twice - once in 'ubifs_jnl_update()' and the second time in
'ubifs_jnl_write_inode()'. However, the second write is not needed
if no commit happened after 'ubifs_jnl_update()'. This patch
checks that condition and avoids writing the deletion inode for
the second time.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy 2008-07-22 13:06:20 +03:00
parent 014eb04b03
commit de94eb558b
3 changed files with 73 additions and 5 deletions

View file

@ -604,6 +604,7 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
release_head(c, BASEHD);
goto out_finish;
}
ui->del_cmtno = c->cmt_no;
}
err = write_head(c, BASEHD, dent, len, &lnum, &dent_offs, sync);
@ -820,6 +821,64 @@ int ubifs_jnl_write_inode(struct ubifs_info *c, const struct inode *inode)
return err;
}
/**
* ubifs_jnl_write_inode - delete an inode.
* @c: UBIFS file-system description object
* @inode: inode to delete
*
* This function deletes inode @inode which includes removing it from orphans,
* deleting it from TNC and, in some cases, writing a deletion inode to the
* journal.
*
* When regular file inodes are unlinked or a directory inode is removed, the
* 'ubifs_jnl_update()' function write corresponding deletion inode and
* direntry to the media, and adds the inode to orphans. After this, when the
* last reference to this inode has been dropped, this function is called. In
* general, it has to write one more deletion inode to the media, because if
* a commit happened between 'ubifs_jnl_update()' and
* 'ubifs_jnl_delete_inode()', the deletion inode is not in the journal
* anymore, and in fact it might be not on the flash anymore, becouse it might
* have been garbage-collected already. And for optimization reasond UBIFS does
* not read the orphan area if it has been unmounted cleanly, so it would have
* no indication in the journal that there is a deleted inode which has to be
* removed from TNC.
*
* However, if there was no commit between 'ubifs_jnl_update()' and
* 'ubifs_jnl_delete_inode()', then there is no need to write the deletion
* inode to the media for the second time. And this is quite typical case.
*
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
int ubifs_jnl_delete_inode(struct ubifs_info *c, const struct inode *inode)
{
int err;
struct ubifs_inode *ui = ubifs_inode(inode);
ubifs_assert(inode->i_nlink == 0);
if (ui->del_cmtno != c->cmt_no)
/* A commit happened for sure */
return ubifs_jnl_write_inode(c, inode);
down_read(&c->commit_sem);
/*
* Check commit number again, because the first test has been done
* without @c->commit_sem, so a commit might have happened.
*/
if (ui->del_cmtno != c->cmt_no) {
up_read(&c->commit_sem);
return ubifs_jnl_write_inode(c, inode);
}
ubifs_delete_orphan(c, inode->i_ino);
err = ubifs_tnc_remove_ino(c, inode->i_ino);
if (err)
ubifs_ro_mode(c, err);
up_read(&c->commit_sem);
return err;
}
/**
* ubifs_jnl_rename - rename a directory entry.
* @c: UBIFS file-system description object
@ -928,6 +987,7 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
release_head(c, BASEHD);
goto out_finish;
}
new_ui->del_cmtno = c->cmt_no;
}
err = write_head(c, BASEHD, dent, len, &lnum, &offs, sync);

View file

@ -341,13 +341,15 @@ static void ubifs_delete_inode(struct inode *inode)
goto out;
ui->ui_size = inode->i_size = 0;
err = ubifs_jnl_write_inode(c, inode);
err = ubifs_jnl_delete_inode(c, inode);
if (err)
/*
* Worst case we have a lost orphan inode wasting space, so a
* simple error message is ok here.
*/
ubifs_err("can't write inode %lu, error %d", inode->i_ino, err);
ubifs_err("can't delete inode %lu, error %d",
inode->i_ino, err);
out:
if (ui->dirty)
ubifs_release_dirty_inode_budget(c, ui);

View file

@ -322,6 +322,8 @@ struct ubifs_gced_idx_leb {
* struct ubifs_inode - UBIFS in-memory inode description.
* @vfs_inode: VFS inode description object
* @creat_sqnum: sequence number at time of creation
* @del_cmtno: commit number corresponding to the time the inode was deleted,
* protected by @c->commit_sem;
* @xattr_size: summarized size of all extended attributes in bytes
* @xattr_cnt: count of extended attributes this inode has
* @xattr_names: sum of lengths of all extended attribute names belonging to
@ -372,7 +374,10 @@ struct ubifs_gced_idx_leb {
*/
struct ubifs_inode {
struct inode vfs_inode;
unsigned long long creat_sqnum;
union {
unsigned long long creat_sqnum;
unsigned long long del_cmtno;
};
unsigned int xattr_size;
unsigned int xattr_cnt;
unsigned int xattr_names;
@ -779,7 +784,7 @@ struct ubifs_compressor {
/**
* struct ubifs_budget_req - budget requirements of an operation.
*
* @fast: non-zero if the budgeting should try to aquire budget quickly and
* @fast: non-zero if the budgeting should try to acquire budget quickly and
* should not try to call write-back
* @recalculate: non-zero if @idx_growth, @data_growth, and @dd_growth fields
* have to be re-calculated
@ -860,7 +865,7 @@ struct ubifs_mount_opts {
* struct ubifs_info - UBIFS file-system description data structure
* (per-superblock).
* @vfs_sb: VFS @struct super_block object
* @bdi: backing device info object to make VFS happy and disable readahead
* @bdi: backing device info object to make VFS happy and disable read-ahead
*
* @highest_inum: highest used inode number
* @vfs_gen: VFS inode generation counter
@ -1402,6 +1407,7 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
int ubifs_jnl_write_data(struct ubifs_info *c, const struct inode *inode,
const union ubifs_key *key, const void *buf, int len);
int ubifs_jnl_write_inode(struct ubifs_info *c, const struct inode *inode);
int ubifs_jnl_delete_inode(struct ubifs_info *c, const struct inode *inode);
int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
const struct dentry *old_dentry,
const struct inode *new_dir,