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ext4: Fix circular locking dependency with migrate and rm.

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In order to prevent a circular locking dependency when an unlink
operation is racing with an ext4 migration, we delay taking i_data_sem
until just before switch the inode format, and use i_mutex to prevent
writes and truncates during the first part of the migration operation.

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Aneesh Kumar K.V 2008-02-10 01:20:05 -05:00 committed by Theodore Ts'o
parent 0040d9875d
commit 8009f9fb30
1 changed files with 74 additions and 43 deletions
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117
fs/ext4/migrate.c
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@ -61,10 +61,9 @@ static int finish_range(handle_t *handle, struct inode *inode,
retval = ext4_journal_restart(handle, needed);
if (retval)
goto err_out;
}
if (needed) {
} else if (needed) {
retval = ext4_journal_extend(handle, needed);
if (retval != 0) {
if (retval) {
/*
* IF not able to extend the journal restart the journal
*/
@ -220,6 +219,26 @@ static int update_tind_extent_range(handle_t *handle, struct inode *inode,
}
static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
{
int retval = 0, needed;
if (handle->h_buffer_credits > EXT4_RESERVE_TRANS_BLOCKS)
return 0;
/*
* We are freeing a blocks. During this we touch
* superblock, group descriptor and block bitmap.
* So allocate a credit of 3. We may update
* quota (user and group).
*/
needed = 3 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
if (ext4_journal_extend(handle, needed) != 0)
retval = ext4_journal_restart(handle, needed);
return retval;
}
static int free_dind_blocks(handle_t *handle,
struct inode *inode, __le32 i_data)
{
@ -234,11 +253,14 @@ static int free_dind_blocks(handle_t *handle,
tmp_idata = (__le32 *)bh->b_data;
for (i = 0; i < max_entries; i++) {
if (tmp_idata[i])
if (tmp_idata[i]) {
extend_credit_for_blkdel(handle, inode);
ext4_free_blocks(handle, inode,
le32_to_cpu(tmp_idata[i]), 1, 1);
}
}
put_bh(bh);
extend_credit_for_blkdel(handle, inode);
ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
return 0;
}
@ -267,29 +289,32 @@ static int free_tind_blocks(handle_t *handle,
}
}
put_bh(bh);
extend_credit_for_blkdel(handle, inode);
ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
return 0;
}
static int free_ind_block(handle_t *handle, struct inode *inode)
static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
{
int retval;
struct ext4_inode_info *ei = EXT4_I(inode);
if (ei->i_data[EXT4_IND_BLOCK])
/* ei->i_data[EXT4_IND_BLOCK] */
if (i_data[0]) {
extend_credit_for_blkdel(handle, inode);
ext4_free_blocks(handle, inode,
le32_to_cpu(ei->i_data[EXT4_IND_BLOCK]), 1, 1);
le32_to_cpu(i_data[0]), 1, 1);
}
if (ei->i_data[EXT4_DIND_BLOCK]) {
retval = free_dind_blocks(handle, inode,
ei->i_data[EXT4_DIND_BLOCK]);
/* ei->i_data[EXT4_DIND_BLOCK] */
if (i_data[1]) {
retval = free_dind_blocks(handle, inode, i_data[1]);
if (retval)
return retval;
}
if (ei->i_data[EXT4_TIND_BLOCK]) {
retval = free_tind_blocks(handle, inode,
ei->i_data[EXT4_TIND_BLOCK]);
/* ei->i_data[EXT4_TIND_BLOCK] */
if (i_data[2]) {
retval = free_tind_blocks(handle, inode, i_data[2]);
if (retval)
return retval;
}
@ -297,15 +322,13 @@ static int free_ind_block(handle_t *handle, struct inode *inode)
}
static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
struct inode *tmp_inode, int retval)
struct inode *tmp_inode)
{
int retval;
__le32 i_data[3];
struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
retval = free_ind_block(handle, inode);
if (retval)
goto err_out;
/*
* One credit accounted for writing the
* i_data field of the original inode
@ -317,6 +340,11 @@ static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
goto err_out;
}
i_data[0] = ei->i_data[EXT4_IND_BLOCK];
i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
down_write(&EXT4_I(inode)->i_data_sem);
/*
* We have the extent map build with the tmp inode.
* Now copy the i_data across
@ -336,8 +364,15 @@ static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
spin_lock(&inode->i_lock);
inode->i_blocks += tmp_inode->i_blocks;
spin_unlock(&inode->i_lock);
up_write(&EXT4_I(inode)->i_data_sem);
/*
* We mark the inode dirty after, because we decrement the
* i_blocks when freeing the indirect meta-data blocks
*/
retval = free_ind_block(handle, inode, i_data);
ext4_mark_inode_dirty(handle, inode);
err_out:
return retval;
}
@ -365,6 +400,7 @@ static int free_ext_idx(handle_t *handle, struct inode *inode,
}
}
put_bh(bh);
extend_credit_for_blkdel(handle, inode);
ext4_free_blocks(handle, inode, block, 1, 1);
return retval;
}
@ -420,7 +456,6 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
*/
return retval;
down_write(&EXT4_I(inode)->i_data_sem);
handle = ext4_journal_start(inode,
EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
@ -454,13 +489,6 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
ext4_orphan_add(handle, tmp_inode);
ext4_journal_stop(handle);
ei = EXT4_I(inode);
i_data = ei->i_data;
memset(&lb, 0, sizeof(lb));
/* 32 bit block address 4 bytes */
max_entries = inode->i_sb->s_blocksize >> 2;
/*
* start with one credit accounted for
* superblock modification.
@ -469,7 +497,20 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
* trascation that created the inode. Later as and
* when we add extents we extent the journal
*/
/*
* inode_mutex prevent write and truncate on the file. Read still goes
* through. We take i_data_sem in ext4_ext_swap_inode_data before we
* switch the inode format to prevent read.
*/
mutex_lock(&(inode->i_mutex));
handle = ext4_journal_start(inode, 1);
ei = EXT4_I(inode);
i_data = ei->i_data;
memset(&lb, 0, sizeof(lb));
/* 32 bit block address 4 bytes */
max_entries = inode->i_sb->s_blocksize >> 2;
for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
if (i_data[i]) {
retval = update_extent_range(handle, tmp_inode,
@ -507,19 +548,6 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
*/
retval = finish_range(handle, tmp_inode, &lb);
err_out:
/*
* We are either freeing extent information or indirect
* blocks. During this we touch superblock, group descriptor
* and block bitmap. Later we mark the tmp_inode dirty
* via ext4_ext_tree_init. So allocate a credit of 4
* We may update quota (user and group).
*
* FIXME!! we may be touching bitmaps in different block groups.
*/
if (ext4_journal_extend(handle,
4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb)) != 0)
ext4_journal_restart(handle,
4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
if (retval)
/*
* Failure case delete the extent information with the
@ -528,7 +556,11 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
free_ext_block(handle, tmp_inode);
else
retval = ext4_ext_swap_inode_data(handle, inode,
tmp_inode, retval);
tmp_inode);
/* We mark the tmp_inode dirty via ext4_ext_tree_init. */
if (ext4_journal_extend(handle, 1) != 0)
ext4_journal_restart(handle, 1);
/*
* Mark the tmp_inode as of size zero
@ -556,8 +588,7 @@ int ext4_ext_migrate(struct inode *inode, struct file *filp,
tmp_inode->i_nlink = 0;
ext4_journal_stop(handle);
up_write(&EXT4_I(inode)->i_data_sem);
mutex_unlock(&(inode->i_mutex));
if (tmp_inode)
iput(tmp_inode);