[ 073/133] ext4: move_extent code cleanup

Greg Kroah-Hartman
2012-10-11T00:12:34Z

From: Dmitry Monakhov <dmonakhov@openvz.org>

commit 03bd8b9b896c8e940f282f540e6b4de90d666b7c upstream.

- Remove usless checks, because it is too late to check that inode != NULL
at the moment it was referenced several times.
- Double lock routines looks very ugly and locking ordering relays on
order of i_ino, but other kernel code rely on order of pointers.
Let's make them simple and clean.
- check that inodes belongs to the same SB as soon as possible.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/move_extent.c | 167 ++++++++++++++------------------------------------
1 file changed, 47 insertions(+), 120 deletions(-)

--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -141,55 +141,21 @@ mext_next_extent(struct inode *inode, st
}

/**
- * mext_check_null_inode - NULL check for two inodes
- *
- * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
- */
-static int
-mext_check_null_inode(struct inode *inode1, struct inode *inode2,
- const char *function, unsigned int line)
-{
- int ret = 0;
-
- if (inode1 == NULL) {
- __ext4_error(inode2->i_sb, function, line,
- "Both inodes should not be NULL: "
- "inode1 NULL inode2 %lu", inode2->i_ino);
- ret = -EIO;
- } else if (inode2 == NULL) {
- __ext4_error(inode1->i_sb, function, line,
- "Both inodes should not be NULL: "
- "inode1 %lu inode2 NULL", inode1->i_ino);
- ret = -EIO;
- }
- return ret;
-}
-
-/**
* double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem
*
- * @orig_inode: original inode structure
- * @donor_inode: donor inode structure
- * Acquire write lock of i_data_sem of the two inodes (orig and donor) by
- * i_ino order.
+ * Acquire write lock of i_data_sem of the two inodes
*/
static void
-double_down_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)
+double_down_write_data_sem(struct inode *first, struct inode *second)
{
- struct inode *first = orig_inode, *second = donor_inode;
+ if (first < second) {
+ down_write(&EXT4_I(first)->i_data_sem);
+ down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
+ } else {
+ down_write(&EXT4_I(second)->i_data_sem);
+ down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING);

- /*
- * Use the inode number to provide the stable locking order instead
- * of its address, because the C language doesn't guarantee you can
- * compare pointers that don't come from the same array.
- */
- if (donor_inode->i_ino < orig_inode->i_ino) {
- first = donor_inode;
- second = orig_inode;
}
-
- down_write(&EXT4_I(first)->i_data_sem);
- down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
}

/**
@@ -969,14 +935,6 @@ mext_check_arguments(struct inode *orig_
return -EINVAL;
}

- /* Files should be in the same ext4 FS */
- if (orig_inode->i_sb != donor_inode->i_sb) {
- ext4_debug("ext4 move extent: The argument files "
- "should be in same FS [ino:orig %lu, donor %lu]\n",
- orig_inode->i_ino, donor_inode->i_ino);
- return -EINVAL;
- }
-
/* Ext4 move extent supports only extent based file */
if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
ext4_debug("ext4 move extent: orig file is not extents "
@@ -1072,35 +1030,19 @@ mext_check_arguments(struct inode *orig_
* @inode1: the inode structure
* @inode2: the inode structure
*
- * Lock two inodes' i_mutex by i_ino order.
- * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
+ * Lock two inodes' i_mutex
*/
-static int
+static void
mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
{
- int ret = 0;
-
- BUG_ON(inode1 == NULL && inode2 == NULL);
-
- ret = mext_check_null_inode(inode1, inode2, __func__, __LINE__);
- if (ret < 0)
- goto out;
-
- if (inode1 == inode2) {
- mutex_lock(&inode1->i_mutex);
- goto out;
- }
-
- if (inode1->i_ino < inode2->i_ino) {
+ BUG_ON(inode1 == inode2);
+ if (inode1 < inode2) {
mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
} else {
mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
}
-
-out:
- return ret;
}

/**
@@ -1109,28 +1051,13 @@ out:
* @inode1: the inode that is released first
* @inode2: the inode that is released second
*
- * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
*/

-static int
+static void
mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)
{
- int ret = 0;
-
- BUG_ON(inode1 == NULL && inode2 == NULL);
-
- ret = mext_check_null_inode(inode1, inode2, __func__, __LINE__);
- if (ret < 0)
- goto out;
-
- if (inode1)
- mutex_unlock(&inode1->i_mutex);
-
- if (inode2 && inode2 != inode1)
- mutex_unlock(&inode2->i_mutex);
-
-out:
- return ret;
+ mutex_unlock(&inode1->i_mutex);
+ mutex_unlock(&inode2->i_mutex);
}

/**
@@ -1187,16 +1114,23 @@ ext4_move_extents(struct file *o_filp, s
ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
ext4_lblk_t rest_blocks;
pgoff_t orig_page_offset = 0, seq_end_page;
- int ret1, ret2, depth, last_extent = 0;
+ int ret, depth, last_extent = 0;
int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
int data_offset_in_page;
int block_len_in_page;
int uninit;

- /* orig and donor should be different file */
- if (orig_inode->i_ino == donor_inode->i_ino) {
+ if (orig_inode->i_sb != donor_inode->i_sb) {
+ ext4_debug("ext4 move extent: The argument files "
+ "should be in same FS [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EINVAL;
+ }
+
+ /* orig and donor should be different inodes */
+ if (orig_inode == donor_inode) {
ext4_debug("ext4 move extent: The argument files should not "
- "be same file [ino:orig %lu, donor %lu]\n",
+ "be same inode [ino:orig %lu, donor %lu]\n",
orig_inode->i_ino, donor_inode->i_ino);
return -EINVAL;
}
@@ -1210,16 +1144,14 @@ ext4_move_extents(struct file *o_filp, s
}

/* Protect orig and donor inodes against a truncate */
- ret1 = mext_inode_double_lock(orig_inode, donor_inode);
- if (ret1 < 0)
- return ret1;
+ mext_inode_double_lock(orig_inode, donor_inode);

/* Protect extent tree against block allocations via delalloc */
double_down_write_data_sem(orig_inode, donor_inode);
/* Check the filesystem environment whether move_extent can be done */
- ret1 = mext_check_arguments(orig_inode, donor_inode, orig_start,
+ ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
donor_start, &len);
- if (ret1)
+ if (ret)
goto out;

file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
@@ -1227,13 +1159,13 @@ ext4_move_extents(struct file *o_filp, s
if (file_end < block_end)
len -= block_end - file_end;

- ret1 = get_ext_path(orig_inode, block_start, &orig_path);
- if (ret1)
+ ret = get_ext_path(orig_inode, block_start, &orig_path);
+ if (ret)
goto out;

/* Get path structure to check the hole */
- ret1 = get_ext_path(orig_inode, block_start, &holecheck_path);
- if (ret1)
+ ret = get_ext_path(orig_inode, block_start, &holecheck_path);
+ if (ret)
goto out;

depth = ext_depth(orig_inode);
@@ -1252,13 +1184,13 @@ ext4_move_extents(struct file *o_filp, s
last_extent = mext_next_extent(orig_inode,
holecheck_path, &ext_cur);
if (last_extent < 0) {
- ret1 = last_extent;
+ ret = last_extent;
goto out;
}
last_extent = mext_next_extent(orig_inode, orig_path,
&ext_dummy);
if (last_extent < 0) {
- ret1 = last_extent;
+ ret = last_extent;
goto out;
}
seq_start = le32_to_cpu(ext_cur->ee_block);
@@ -1272,7 +1204,7 @@ ext4_move_extents(struct file *o_filp, s
if (le32_to_cpu(ext_cur->ee_block) > block_end) {
ext4_debug("ext4 move extent: The specified range of file "
"may be the hole\n");
- ret1 = -EINVAL;
+ ret = -EINVAL;
goto out;
}

@@ -1292,7 +1224,7 @@ ext4_move_extents(struct file *o_filp, s
last_extent = mext_next_extent(orig_inode, holecheck_path,
&ext_cur);
if (last_extent < 0) {
- ret1 = last_extent;
+ ret = last_extent;
break;
}
add_blocks = ext4_ext_get_actual_len(ext_cur);
@@ -1349,18 +1281,18 @@ ext4_move_extents(struct file *o_filp, s
orig_page_offset,
data_offset_in_page,
block_len_in_page, uninit,
- &ret1);
+ &ret);

/* Count how many blocks we have exchanged */
*moved_len += block_len_in_page;
- if (ret1 < 0)
+ if (ret < 0)
break;
if (*moved_len > len) {
EXT4_ERROR_INODE(orig_inode,
"We replaced blocks too much! "
"sum of replaced: %llu requested: %llu",
*moved_len, len);
- ret1 = -EIO;
+ ret = -EIO;
break;
}

@@ -1374,22 +1306,22 @@ ext4_move_extents(struct file *o_filp, s
}

double_down_write_data_sem(orig_inode, donor_inode);
- if (ret1 < 0)
+ if (ret < 0)
break;

/* Decrease buffer counter */
if (holecheck_path)
ext4_ext_drop_refs(holecheck_path);
- ret1 = get_ext_path(orig_inode, seq_start, &holecheck_path);
- if (ret1)
+ ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
+ if (ret)
break;
depth = holecheck_path->p_depth;

/* Decrease buffer counter */
if (orig_path)
ext4_ext_drop_refs(orig_path);
- ret1 = get_ext_path(orig_inode, seq_start, &orig_path);
- if (ret1)
+ ret = get_ext_path(orig_inode, seq_start, &orig_path);
+ if (ret)
break;

ext_cur = holecheck_path[depth].p_ext;
@@ -1412,12 +1344,7 @@ out:
kfree(holecheck_path);
}
double_up_write_data_sem(orig_inode, donor_inode);
- ret2 = mext_inode_double_unlock(orig_inode, donor_inode);
+ mext_inode_double_unlock(orig_inode, donor_inode);

- if (ret1)
- return ret1;
- else if (ret2)
- return ret2;
-
- return 0;
+ return ret;
}