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Commit de94eb55 authored by Artem Bityutskiy's avatar Artem Bityutskiy
Browse files

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: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
parent 014eb04b

fs/ubifs/journal.c

+60 −0
Original line number Diff line number Diff line
@@ -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);

fs/ubifs/super.c

+4 −2
Original line number Diff line number Diff line
@@ -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);

fs/ubifs/ubifs.h

+9 −3
Original line number Diff line number Diff line
@@ -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;

	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,