The block allocation functions can use a huge amount of cleanup to
make them more understandable. This is just a starting point to make
life easier.
- Ted
The function ext4_da_get_block_write() is called in exactly one write,
and the last argument, create, is always 1. Remove it to simplify the
code slightly.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4909d3d..0968e6d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1994,7 +1994,7 @@ static void ext4_print_free_blocks(struct inode *inode)
#define EXT4_DELALLOC_RSVED 1
static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create)
+ struct buffer_head *bh_result)
{
int ret;
unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
@@ -2004,7 +2004,7 @@ 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_wrap(handle, inode, iblock, max_blocks,
- bh_result, create, 0, EXT4_DELALLOC_RSVED);
+ bh_result, 1, 0, EXT4_DELALLOC_RSVED);
if (ret <= 0)
return ret;
@@ -2069,7 +2069,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
if (!new.b_size)
return 0;
- err = ext4_da_get_block_write(mpd->inode, next, &new, 1);
+ err = ext4_da_get_block_write(mpd->inode, next, &new);
if (err) {
/*
* If get block returns with error we simply
--
1.6.3.rc4.1.g3e14.dirty
Enforce that noalloc_get_block_write() is only called to map one block
at a time, and that it always is successful in finding a mapping for
given an inode's logical block block number if it is called with
create == 1.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9431d50..114fa4f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2413,11 +2413,14 @@ static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
int ret = 0;
unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
+ BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
+
/*
* 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);
+ BUG_ON(create && ret == 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
--
1.6.3.rc4.1.g3e14.dirty
The static function ext4_get_blocks_handle() is badly named. Of
*course* it takes a handle. Since its counterpart for extent-based
file is ext4_ext_get_blocks(), rename it to be ext4_ind_get_blocks().
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0968e6d..61a9579 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -914,7 +914,7 @@ err_out:
* down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
* (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
*/
-static int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
+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)
@@ -1129,7 +1129,7 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
* mapped.
*
* If file type is extents based, it will call ext4_ext_get_blocks(),
- * Otherwise, call with ext4_get_blocks_handle() to handle indirect mapping
+ * Otherwise, call with ext4_ind_get_blocks() to handle indirect mapping
* based files
*
* On success, it returns the number of blocks being mapped or allocate.
@@ -1160,8 +1160,8 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
bh, 0, 0);
} else {
- retval = ext4_get_blocks_handle(handle,
- inode, block, max_blocks, bh, 0, 0);
+ retval = ext4_ind_get_blocks(handle, inode, block, max_blocks,
+ bh, 0, 0);
}
up_read((&EXT4_I(inode)->i_data_sem));
@@ -1209,7 +1209,7 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
bh, create, extend_disksize);
} else {
- retval = ext4_get_blocks_handle(handle, inode, block,
+ retval = ext4_ind_get_blocks(handle, inode, block,
max_blocks, bh, create, extend_disksize);
if (retval > 0 && buffer_new(bh)) {
@@ -1291,7 +1291,7 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
err = ext4_get_blocks_wrap(handle, inode, block, 1,
&dummy, create, 1, 0);
/*
- * ext4_get_blocks_handle() returns number of blocks
+ * ext4_get_blocks_wrap() returns number of blocks
* mapped. 0 in case of a HOLE.
*/
if (err > 0) {
--
1.6.3.rc4.1.g3e14.dirty
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" <[email protected]>
---
fs/ext4/dir.c | 2 +-
fs/ext4/ext4.h | 22 +++++++++++++++-------
fs/ext4/extents.c | 22 +++++++++++-----------
fs/ext4/inode.c | 44 +++++++++++++++++++++++---------------------
4 files changed, 50 insertions(+), 40 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 5f7223f..c2b3461 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
@@ -1616,8 +1626,7 @@ 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 *);
@@ -1625,8 +1634,7 @@ 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 bc54bb1..e041248 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2777,7 +2777,7 @@ 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;
@@ -2796,7 +2796,7 @@ 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
@@ -2862,9 +2862,9 @@ 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;
/*
@@ -2896,7 +2896,7 @@ 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
@@ -2925,10 +2925,10 @@ 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 */
@@ -2959,7 +2959,7 @@ 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) {
@@ -2976,7 +2976,7 @@ 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);
@@ -2987,7 +2987,7 @@ 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:
@@ -3146,7 +3146,7 @@ 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 466b7b5..48c8f81 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;
/*
@@ -1199,7 +1199,7 @@ 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
@@ -1207,10 +1207,10 @@ 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)) {
/*
@@ -1223,7 +1223,7 @@ 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
@@ -1263,7 +1263,7 @@ 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;
@@ -1282,16 +1282,19 @@ 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)
@@ -1991,7 +1994,6 @@ 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)
{
@@ -2003,7 +2005,8 @@ 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;
@@ -2343,7 +2346,7 @@ 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 */
/*
@@ -2387,8 +2390,7 @@ 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.rc4.1.g3e14.dirty
Another function rename for clarity's sake. The _wrap prefix simply
confuses people, and didn't add much people trying to follow the code
paths.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/dir.c | 3 +--
fs/ext4/ext4.h | 8 ++++----
fs/ext4/extents.c | 6 +++---
fs/ext4/inode.c | 29 ++++++++++++++---------------
4 files changed, 22 insertions(+), 24 deletions(-)
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index b647899..052d637 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -131,8 +131,7 @@ static int ext4_readdir(struct file *filp,
struct buffer_head *bh = NULL;
map_bh.b_state = 0;
- err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh,
- 0, 0, 0);
+ err = ext4_get_blocks(NULL, inode, blk, 1, &map_bh, 0, 0, 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 149e02d..5f7223f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1623,10 +1623,10 @@ extern void ext4_ext_init(struct super_block *);
extern void ext4_ext_release(struct super_block *);
extern long ext4_fallocate(struct inode *inode, int mode, loff_t offset,
loff_t len);
-extern int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode,
- sector_t block, unsigned int max_blocks,
- struct buffer_head *bh, int create,
- int extend_disksize, int flag);
+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);
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 abf5e5d..bc54bb1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3144,9 +3144,9 @@ retry:
break;
}
map_bh.b_state = 0;
- ret = ext4_get_blocks_wrap(handle, inode, block,
- max_blocks, &map_bh,
- EXT4_CREATE_UNINITIALIZED_EXT, 0, 0);
+ ret = ext4_get_blocks(handle, inode, block,
+ max_blocks, &map_bh,
+ EXT4_CREATE_UNINITIALIZED_EXT, 0, 0);
if (ret <= 0) {
#ifdef EXT4FS_DEBUG
WARN_ON(ret <= 0);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 61a9579..466b7b5 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1121,7 +1121,7 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
}
/*
- * The ext4_get_blocks_wrap() function try to look up the requested blocks,
+ * The ext4_get_blocks() function tries to look up the requested blocks,
* and returns if the blocks are already mapped.
*
* Otherwise it takes the write lock of the i_data_sem and allocate blocks
@@ -1142,9 +1142,9 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
*
* It returns the error in case of allocation failure.
*/
-int ext4_get_blocks_wrap(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 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 retval;
@@ -1262,8 +1262,8 @@ int ext4_get_block(struct inode *inode, sector_t iblock,
started = 1;
}
- ret = ext4_get_blocks_wrap(handle, inode, iblock,
- max_blocks, bh_result, create, 0, 0);
+ ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
+ create, 0, 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
@@ -1288,10 +1288,9 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
dummy.b_state = 0;
dummy.b_blocknr = -1000;
buffer_trace_init(&dummy.b_history);
- err = ext4_get_blocks_wrap(handle, inode, block, 1,
- &dummy, create, 1, 0);
+ err = ext4_get_blocks(handle, inode, block, 1, &dummy, create, 1, 0);
/*
- * ext4_get_blocks_wrap() returns number of blocks
+ * ext4_get_blocks() returns number of blocks
* mapped. 0 in case of a HOLE.
*/
if (err > 0) {
@@ -2003,8 +2002,8 @@ 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_wrap(handle, inode, iblock, max_blocks,
- bh_result, 1, 0, EXT4_DELALLOC_RSVED);
+ ret = ext4_get_blocks(handle, inode, iblock, max_blocks,
+ bh_result, 1, 0, EXT4_DELALLOC_RSVED);
if (ret <= 0)
return ret;
@@ -2344,7 +2343,7 @@ 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_wrap(NULL, inode, iblock, 1, bh_result, 0, 0, 0);
+ ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0, 0, 0);
if ((ret == 0) && !buffer_delay(bh_result)) {
/* the block isn't (pre)allocated yet, let's reserve space */
/*
@@ -2388,8 +2387,8 @@ 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_wrap(NULL, inode, iblock, max_blocks,
- bh_result, 0, 0, 0);
+ ret = ext4_get_blocks(NULL, inode, iblock, max_blocks,
+ bh_result, 0, 0, 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
@@ -5015,7 +5014,7 @@ int ext4_writepage_trans_blocks(struct inode *inode)
* Calculate the journal credits for a chunk of data modification.
*
* This is called from DIO, fallocate or whoever calling
- * ext4_get_blocks_wrap() to map/allocate a chunk of contigous disk blocks.
+ * ext4_get_blocks() to map/allocate a chunk of contigous disk blocks.
*
* journal buffers for data blocks are not included here, as DIO
* and fallocate do no need to journal data buffers.
--
1.6.3.rc4.1.g3e14.dirty
This adds more docmentation to various internal functions in
fs/ext4/inode.c, most notably ext4_ind_get_blocks(),
ext4_da_get_block_write(), ext4_da_get_block_prep(),
ext4_normal_get_block_write().
In addition, the static function ext4_normal_get_block_write() has
been renamed noalloc_get_block_write(), since it is used in many
places far beyond ext4_normal_writepage().
Plenty of warnings have been added to the noalloc_get_block_write()
function, since the way it is used is amazingly fragile.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 73 ++++++++++++++++++++++++++++++++++++-------------------
1 files changed, 48 insertions(+), 25 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 48c8f81..9431d50 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -892,6 +892,10 @@ err_out:
}
/*
+ * The ext4_ind_get_blocks() function handles non-extents inodes
+ * (i.e., using the traditional indirect/double-indirect i_blocks
+ * scheme) for ext4_get_blocks().
+ *
* Allocation strategy is simple: if we have to allocate something, we will
* have to go the whole way to leaf. So let's do it before attaching anything
* to tree, set linkage between the newborn blocks, write them if sync is
@@ -909,10 +913,11 @@ err_out:
* return = 0, if plain lookup failed.
* return < 0, error case.
*
- *
- * Need to be called with
- * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
- * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
+ * The ext4_ind_get_blocks() function should be called with
+ * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
+ * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
+ * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
+ * blocks.
*/
static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock, unsigned int maxblocks,
@@ -1994,6 +1999,12 @@ static void ext4_print_free_blocks(struct inode *inode)
return;
}
+/*
+ * This function is used by mpage_da_map_blocks(). We separate it out
+ * as a separate function just to make life easier, and because
+ * mpage_da_map_blocks() used to be a generic function that took a
+ * get_block_t.
+ */
static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result)
{
@@ -2025,8 +2036,8 @@ static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
/*
* Update on-disk size along with block allocation we don't
- * use 'extend_disksize' as size may change within already
- * allocated block -bzzz
+ * use EXT4_GET_BLOCKS_EXTEND_DISKSIZE as size may change
+ * within already allocated block -bzzz
*/
disksize = ((loff_t) iblock + ret) << inode->i_blkbits;
if (disksize > i_size_read(inode))
@@ -2318,8 +2329,9 @@ static int __mpage_da_writepage(struct page *page,
}
/*
- * this is a special callback for ->write_begin() only
- * it's intention is to return mapped block or reserve space
+ * This is a special get_blocks_t callback which is used by
+ * ext4_da_write_begin(). It will either return mapped block or
+ * reserve space for a single block.
*
* For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
* We also have b_blocknr = -1 and b_bdev initialized properly
@@ -2327,7 +2339,6 @@ static int __mpage_da_writepage(struct page *page,
* For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
* We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
* initialized properly.
- *
*/
static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
@@ -2380,7 +2391,23 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
return ret;
}
-static int ext4_normal_get_block_write(struct inode *inode, sector_t iblock,
+/*
+ * This function is used as a standard get_block_t calback function
+ * when there is no desire to allocate any blocks. It is used as a
+ * callback function for block_prepare_write(), nobh_writepage(), and
+ * block_write_full_page(). These functions should only try to map a
+ * single block at a time.
+ *
+ * Since this function doesn't do block allocations even if the caller
+ * requests it by passing in create=1, it is critically important that
+ * any caller checks to make sure that any buffer heads are returned
+ * by this function are either all already mapped or marked for
+ * delayed allocation before calling nobh_writepage() or
+ * block_write_full_page(). Otherwise, b_blocknr could be left
+ * unitialized, and the page write functions will be taken by
+ * surprise.
+ */
+static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
int ret = 0;
@@ -2453,7 +2480,7 @@ static int ext4_da_writepage(struct page *page,
* do block allocation here.
*/
ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
- ext4_normal_get_block_write);
+ noalloc_get_block_write);
if (!ret) {
page_bufs = page_buffers(page);
/* check whether all are mapped and non delay */
@@ -2478,11 +2505,10 @@ static int ext4_da_writepage(struct page *page,
}
if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
- ret = nobh_writepage(page, ext4_normal_get_block_write, wbc);
+ ret = nobh_writepage(page, noalloc_get_block_write, wbc);
else
- ret = block_write_full_page(page,
- ext4_normal_get_block_write,
- wbc);
+ ret = block_write_full_page(page, noalloc_get_block_write,
+ wbc);
return ret;
}
@@ -2794,7 +2820,7 @@ retry:
*pagep = page;
ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
- ext4_da_get_block_prep);
+ ext4_da_get_block_prep);
if (ret < 0) {
unlock_page(page);
ext4_journal_stop(handle);
@@ -3102,12 +3128,10 @@ static int __ext4_normal_writepage(struct page *page,
struct inode *inode = page->mapping->host;
if (test_opt(inode->i_sb, NOBH))
- return nobh_writepage(page,
- ext4_normal_get_block_write, wbc);
+ return nobh_writepage(page, noalloc_get_block_write, wbc);
else
- return block_write_full_page(page,
- ext4_normal_get_block_write,
- wbc);
+ return block_write_full_page(page, noalloc_get_block_write,
+ wbc);
}
static int ext4_normal_writepage(struct page *page,
@@ -3159,7 +3183,7 @@ static int __ext4_journalled_writepage(struct page *page,
int err;
ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
- ext4_normal_get_block_write);
+ noalloc_get_block_write);
if (ret != 0)
goto out_unlock;
@@ -3244,9 +3268,8 @@ static int ext4_journalled_writepage(struct page *page,
* really know unless we go poke around in the buffer_heads.
* But block_write_full_page will do the right thing.
*/
- return block_write_full_page(page,
- ext4_normal_get_block_write,
- wbc);
+ return block_write_full_page(page, noalloc_get_block_write,
+ wbc);
}
no_write:
redirty_page_for_writepage(wbc, page);
--
1.6.3.rc4.1.g3e14.dirty