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Message-Id: <1218622675-28853-14-git-send-email-dedekind@infradead.org>
Date: Wed, 13 Aug 2008 13:17:42 +0300
From: Artem Bityutskiy <dedekind@...radead.org>
To: linux-kernel@...r.kernel.org
Cc: Adrian Hunter <ext-adrian.hunter@...ia.com>,
Zoltan Sogor <weth@....u-szeged.hu>,
Christoph Hellwig <hch@....de>
Subject: [PATCH] UBIFS: optimize deletions
From: Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
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@...ia.com>
---
fs/ubifs/journal.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ubifs/super.c | 6 +++-
fs/ubifs/ubifs.h | 12 +++++++--
3 files changed, 73 insertions(+), 5 deletions(-)
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 3bc3fc9..0bcee7d 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -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);
@@ -821,6 +822,64 @@ out_free:
}
/**
+ * 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
* @old_dir: parent inode of directory entry to rename
@@ -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);
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index cf1fb6c..6cc4175 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -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);
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 21502b6..dfb4b93 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -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,
--
1.5.4.1
--
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