[PATCH 31/49] ext4: Define a new set of flags for ext4_get_blocks()

Theodore Ts'o
2009-06-08T19:30:49Z

The functions ext4_get_blocks(), ext4_ext_get_blocks(), and
ext4_ind_get_blocks() used an ad-hoc set of integer variables used as
boolean flags passed in as arguments. Use a single flags parameter
and a setandard set of bitfield flags instead. This saves space on
the call stack, and it also makes the code a bit more understandable.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
fs/ext4/dir.c | 2 +-
fs/ext4/ext4.h | 22 ++++++++++++++------
fs/ext4/extents.c | 22 ++++++++++----------
fs/ext4/inode.c | 57 +++++++++++++++++++++++++++-------------------------
4 files changed, 57 insertions(+), 46 deletions(-)

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 052d637..9dc9316 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -131,7 +131,7 @@ static int ext4_readdir(struct file *filp,
struct buffer_head *bh = NULL;

map_bh.b_state = 0;
- err = ext4_get_blocks(NULL, inode, blk, 1, &map_bh, 0, 0, 0);
+ err = ext4_get_blocks(NULL, inode, blk, 1, &map_bh, 0);
if (err > 0) {
pgoff_t index = map_bh.b_blocknr >>
(PAGE_CACHE_SHIFT - inode->i_blkbits);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 5dc8368..17feb4a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -314,10 +314,20 @@ struct ext4_new_group_data {
};

/*
- * Following is used by preallocation code to tell get_blocks() that we
- * want uninitialzed extents.
+ * Flags used by ext4_get_blocks()
*/
-#define EXT4_CREATE_UNINITIALIZED_EXT 2
+ /* Allocate any needed blocks and/or convert an unitialized
+ extent to be an initialized ext4 */
+#define EXT4_GET_BLOCKS_CREATE 1
+ /* Request the creation of an unitialized extent */
+#define EXT4_GET_BLOCKS_UNINIT_EXT 2
+#define EXT4_GET_BLOCKS_CREATE_UNINIT_EXT (EXT4_GET_BLOCKS_UNINIT_EXT|\
+ EXT4_GET_BLOCKS_CREATE)
+ /* Update the ext4_inode_info i_disksize field */
+#define EXT4_GET_BLOCKS_EXTEND_DISKSIZE 4
+ /* Caller is from the delayed allocation writeout path,
+ so the filesystem blocks have already been accounted for */
+#define EXT4_GET_BLOCKS_DELALLOC_RESERVE 8

/*
* ioctl commands
@@ -1610,8 +1620,7 @@ extern int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks,
int chunk);
extern int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock, unsigned int max_blocks,
- struct buffer_head *bh_result,
- int create, int extend_disksize);
+ struct buffer_head *bh_result, int flags);
extern void ext4_ext_truncate(struct inode *);
extern void ext4_ext_init(struct super_block *);
extern void ext4_ext_release(struct super_block *);
@@ -1619,8 +1628,7 @@ extern long ext4_fallocate(struct inode *inode, int mode, loff_t offset,
loff_t len);
extern int ext4_get_blocks(handle_t *handle, struct inode *inode,
sector_t block, unsigned int max_blocks,
- struct buffer_head *bh, int create,
- int extend_disksize, int flag);
+ struct buffer_head *bh, int flags);
extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len);

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 7e7d02d..27c383c 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2784,7 +2784,7 @@ fix_extent_len:
int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock,
unsigned int max_blocks, struct buffer_head *bh_result,
- int create, int extend_disksize)
+ int flags)
{
struct ext4_ext_path *path = NULL;
struct ext4_extent_header *eh;
@@ -2803,7 +2803,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
cache_type = ext4_ext_in_cache(inode, iblock, &newex);
if (cache_type) {
if (cache_type == EXT4_EXT_CACHE_GAP) {
- if (!create) {
+ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
/*
* block isn't allocated yet and
* user doesn't want to allocate it
@@ -2869,9 +2869,9 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
EXT4_EXT_CACHE_EXTENT);
goto out;
}
- if (create == EXT4_CREATE_UNINITIALIZED_EXT)
+ if (flags & EXT4_GET_BLOCKS_UNINIT_EXT)
goto out;
- if (!create) {
+ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
if (allocated > max_blocks)
allocated = max_blocks;
/*
@@ -2903,7 +2903,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
* requested block isn't allocated yet;
* we couldn't try to create block if create flag is zero
*/
- if (!create) {
+ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
/*
* put just found gap into cache to speed up
* subsequent requests
@@ -2932,10 +2932,10 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
* EXT_UNINIT_MAX_LEN.
*/
if (max_blocks > EXT_INIT_MAX_LEN &&
- create != EXT4_CREATE_UNINITIALIZED_EXT)
+ !(flags & EXT4_GET_BLOCKS_UNINIT_EXT))
max_blocks = EXT_INIT_MAX_LEN;
else if (max_blocks > EXT_UNINIT_MAX_LEN &&
- create == EXT4_CREATE_UNINITIALIZED_EXT)
+ (flags & EXT4_GET_BLOCKS_UNINIT_EXT))
max_blocks = EXT_UNINIT_MAX_LEN;

/* Check if we can really insert (iblock)::(iblock+max_blocks) extent */
@@ -2966,7 +2966,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
/* try to insert new extent into found leaf and return */
ext4_ext_store_pblock(&newex, newblock);
newex.ee_len = cpu_to_le16(ar.len);
- if (create == EXT4_CREATE_UNINITIALIZED_EXT) /* Mark uninitialized */
+ if (flags & EXT4_GET_BLOCKS_UNINIT_EXT) /* Mark uninitialized */
ext4_ext_mark_uninitialized(&newex);
err = ext4_ext_insert_extent(handle, inode, path, &newex);
if (err) {
@@ -2983,7 +2983,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
newblock = ext_pblock(&newex);
allocated = ext4_ext_get_actual_len(&newex);
outnew:
- if (extend_disksize) {
+ if (flags & EXT4_GET_BLOCKS_EXTEND_DISKSIZE) {
disksize = ((loff_t) iblock + ar.len) << inode->i_blkbits;
if (disksize > i_size_read(inode))
disksize = i_size_read(inode);
@@ -2994,7 +2994,7 @@ outnew:
set_buffer_new(bh_result);

/* Cache only when it is _not_ an uninitialized extent */
- if (create != EXT4_CREATE_UNINITIALIZED_EXT)
+ if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0)
ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
EXT4_EXT_CACHE_EXTENT);
out:
@@ -3153,7 +3153,7 @@ retry:
map_bh.b_state = 0;
ret = ext4_get_blocks(handle, inode, block,
max_blocks, &map_bh,
- EXT4_CREATE_UNINITIALIZED_EXT, 0, 0);
+ EXT4_GET_BLOCKS_CREATE_UNINIT_EXT);
if (ret <= 0) {
#ifdef EXT4FS_DEBUG
WARN_ON(ret <= 0);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index a9a9b9b..8b7564d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -917,7 +917,7 @@ err_out:
static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock, unsigned int maxblocks,
struct buffer_head *bh_result,
- int create, int extend_disksize)
+ int flags)
{
int err = -EIO;
ext4_lblk_t offsets[4];
@@ -934,7 +934,7 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,

J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
- J_ASSERT(handle != NULL || create == 0);
+ J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
depth = ext4_block_to_path(inode, iblock, offsets,
&blocks_to_boundary);

@@ -963,7 +963,7 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
}

/* Next simple case - plain lookup or failed read of indirect block */
- if (!create || err == -EIO)
+ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
goto cleanup;

/*
@@ -1002,7 +1002,7 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
* protect it if you're about to implement concurrent
* ext4_get_block() -bzzz
*/
- if (!err && extend_disksize) {
+ if (!err && (flags & EXT4_GET_BLOCKS_EXTEND_DISKSIZE)) {
disksize = ((loff_t) iblock + count) << inode->i_blkbits;
if (disksize > i_size_read(inode))
disksize = i_size_read(inode);
@@ -1144,7 +1144,7 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
*/
int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
unsigned int max_blocks, struct buffer_head *bh,
- int create, int extend_disksize, int flag)
+ int flags)
{
int retval;

@@ -1158,15 +1158,15 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
down_read((&EXT4_I(inode)->i_data_sem));
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
- bh, 0, 0);
+ bh, 0);
} else {
retval = ext4_ind_get_blocks(handle, inode, block, max_blocks,
- bh, 0, 0);
+ bh, 0);
}
up_read((&EXT4_I(inode)->i_data_sem));

/* If it is only a block(s) look up */
- if (!create)
+ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
return retval;

/*
@@ -1205,7 +1205,7 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
* let the underlying get_block() function know to
* avoid double accounting
*/
- if (flag)
+ if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
EXT4_I(inode)->i_delalloc_reserved_flag = 1;
/*
* We need to check for EXT4 here because migrate
@@ -1213,10 +1213,10 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
*/
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
- bh, create, extend_disksize);
+ bh, flags);
} else {
retval = ext4_ind_get_blocks(handle, inode, block,
- max_blocks, bh, create, extend_disksize);
+ max_blocks, bh, flags);

if (retval > 0 && buffer_new(bh)) {
/*
@@ -1229,7 +1229,7 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
}
}

- if (flag) {
+ if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
EXT4_I(inode)->i_delalloc_reserved_flag = 0;
/*
* Update reserved blocks/metadata blocks
@@ -1269,7 +1269,7 @@ int ext4_get_block(struct inode *inode, sector_t iblock,
}

ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
- create, 0, 0);
+ create ? EXT4_GET_BLOCKS_CREATE : 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
@@ -1288,16 +1288,19 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
{
struct buffer_head dummy;
int fatal = 0, err;
+ int flags = EXT4_GET_BLOCKS_EXTEND_DISKSIZE;

J_ASSERT(handle != NULL || create == 0);

dummy.b_state = 0;
dummy.b_blocknr = -1000;
buffer_trace_init(&dummy.b_history);
- err = ext4_get_blocks(handle, inode, block, 1, &dummy, create, 1, 0);
+ if (create)
+ flags |= EXT4_GET_BLOCKS_CREATE;
+ err = ext4_get_blocks(handle, inode, block, 1, &dummy, flags);
/*
- * ext4_get_blocks() returns number of blocks
- * mapped. 0 in case of a HOLE.
+ * ext4_get_blocks() returns number of blocks mapped. 0 in
+ * case of a HOLE.
*/
if (err > 0) {
if (err > 1)
@@ -1997,7 +2000,6 @@ static void ext4_print_free_blocks(struct inode *inode)
return;
}

-#define EXT4_DELALLOC_RSVED 1
static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result)
{
@@ -2009,7 +2011,8 @@ static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
handle = ext4_journal_current_handle();
BUG_ON(!handle);
ret = ext4_get_blocks(handle, inode, iblock, max_blocks,
- bh_result, 1, 0, EXT4_DELALLOC_RSVED);
+ bh_result, EXT4_GET_BLOCKS_CREATE|
+ EXT4_GET_BLOCKS_DELALLOC_RESERVE);
if (ret <= 0)
return ret;

@@ -2065,16 +2068,17 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
return 0;
/*
* We need to make sure the BH_Delay flag is passed down to
- * ext4_da_get_block_write(), since it calls
- * ext4_get_blocks() with the EXT4_DELALLOC_RSVED flag.
- * This flag causes ext4_get_blocks() to call
+ * ext4_da_get_block_write(), since it calls ext4_get_blocks()
+ * with the EXT4_GET_BLOCKS_DELALLOC_RESERVE flag. This flag
+ * causes ext4_get_blocks() to call
* ext4_da_update_reserve_space() if the passed buffer head
* has the BH_Delay flag set. In the future, once we clean up
- * the interfaces to ext4_get_blocks(), we should pass in
- * a separate flag which requests that the delayed allocation
+ * the interfaces to ext4_get_blocks(), we should pass in a
+ * separate flag which requests that the delayed allocation
* statistics should be updated, instead of depending on the
* state information getting passed down via the map_bh's
- * state bitmasks plus the magic EXT4_DELALLOC_RSVED flag.
+ * state bitmasks plus the magic
+ * EXT4_GET_BLOCKS_DELALLOC_RESERVE flag.
*/
new.b_state = mpd->b_state & (1 << BH_Delay);
new.b_blocknr = 0;
@@ -2362,7 +2366,7 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
* preallocated blocks are unmapped but should treated
* the same as allocated blocks.
*/
- ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0, 0, 0);
+ ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0);
if ((ret == 0) && !buffer_delay(bh_result)) {
/* the block isn't (pre)allocated yet, let's reserve space */
/*
@@ -2406,8 +2410,7 @@ static int ext4_normal_get_block_write(struct inode *inode, sector_t iblock,
* we don't want to do block allocation in writepage
* so call get_block_wrap with create = 0
*/
- ret = ext4_get_blocks(NULL, inode, iblock, max_blocks,
- bh_result, 0, 0, 0);
+ ret = ext4_get_blocks(NULL, inode, iblock, max_blocks, bh_result, 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
--
1.6.3.2.1.gb9f7d.dirty