Commit acd15a83 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2: (56 commits)
  ocfs2: Make cached block reads the common case.
  ocfs2: Kill the last naked wait_on_buffer() for cached reads.
  ocfs2: Move ocfs2_bread() into dir.c
  ocfs2: Simplify ocfs2_read_block()
  ocfs2: Require an inode for ocfs2_read_block(s)().
  ocfs2: Separate out sync reads from ocfs2_read_blocks()
  ocfs2: Refactor xattr list and remove ocfs2_xattr_handler().
  ocfs2: Calculate EA hash only by its suffix.
  ocfs2: Move trusted and user attribute support into xattr.c
  ocfs2: Uninline ocfs2_xattr_name_hash()
  ocfs2: Don't check for NULL before brelse()
  ocfs2: use smaller counters in ocfs2_remove_xattr_clusters_from_cache
  ocfs2: Documentation update for user_xattr / nouser_xattr mount options
  ocfs2: make la_debug_mutex static
  ocfs2: Remove pointless !!
  ocfs2: Add empty bucket support in xattr.
  ocfs2/xattr.c: Fix a bug when inserting xattr.
  ocfs2: Add xattr mount option in ocfs2_show_options()
  ocfs2: Switch over to JBD2.
  ocfs2: Add the 'inode64' mount option.
  ...
parents 72f22b1e d4a8c93c
......@@ -76,3 +76,9 @@ localalloc=8(*) Allows custom localalloc size in MB. If the value is too
large, the fs will silently revert it to the default.
Localalloc is not enabled for local mounts.
localflocks This disables cluster aware flock.
inode64 Indicates that Ocfs2 is allowed to create inodes at
any location in the filesystem, including those which
will result in inode numbers occupying more than 32
bits of significance.
user_xattr (*) Enables Extended User Attributes.
nouser_xattr Disables Extended User Attributes.
......@@ -220,17 +220,16 @@ config JBD
tristate
help
This is a generic journalling layer for block devices. It is
currently used by the ext3 and OCFS2 file systems, but it could
also be used to add journal support to other file systems or block
currently used by the ext3 file system, but it could also be
used to add journal support to other file systems or block
devices such as RAID or LVM.
If you are using the ext3 or OCFS2 file systems, you need to
say Y here. If you are not using ext3 OCFS2 then you will probably
want to say N.
If you are using the ext3 file system, you need to say Y here.
If you are not using ext3 then you will probably want to say N.
To compile this device as a module, choose M here: the module will be
called jbd. If you are compiling ext3 or OCFS2 into the kernel,
you cannot compile this code as a module.
called jbd. If you are compiling ext3 into the kernel, you
cannot compile this code as a module.
config JBD_DEBUG
bool "JBD (ext3) debugging support"
......@@ -254,15 +253,16 @@ config JBD2
help
This is a generic journaling layer for block devices that support
both 32-bit and 64-bit block numbers. It is currently used by
the ext4 filesystem, but it could also be used to add
the ext4 and OCFS2 filesystems, but it could also be used to add
journal support to other file systems or block devices such
as RAID or LVM.
If you are using ext4, you need to say Y here. If you are not
using ext4 then you will probably want to say N.
If you are using ext4 or OCFS2, you need to say Y here.
If you are not using ext4 or OCFS2 then you will
probably want to say N.
To compile this device as a module, choose M here. The module will be
called jbd2. If you are compiling ext4 into the kernel,
called jbd2. If you are compiling ext4 or OCFS2 into the kernel,
you cannot compile this code as a module.
config JBD2_DEBUG
......@@ -448,7 +448,7 @@ config OCFS2_FS
tristate "OCFS2 file system support"
depends on NET && SYSFS
select CONFIGFS_FS
select JBD
select JBD2
select CRC32
help
OCFS2 is a general purpose extent based shared disk cluster file
......@@ -519,6 +519,16 @@ config OCFS2_DEBUG_FS
this option for debugging only as it is likely to decrease
performance of the filesystem.
config OCFS2_COMPAT_JBD
bool "Use JBD for compatibility"
depends on OCFS2_FS
default n
select JBD
help
The ocfs2 filesystem now uses JBD2 for its journalling. JBD2
is backwards compatible with JBD. It is safe to say N here.
However, if you really want to use the original JBD, say Y here.
endif # BLOCK
config DNOTIFY
......
......@@ -34,7 +34,8 @@ ocfs2-objs := \
symlink.o \
sysfile.o \
uptodate.o \
ver.o
ver.o \
xattr.o
ocfs2_stackglue-objs := stackglue.o
ocfs2_stack_o2cb-objs := stack_o2cb.o
......
This diff is collapsed.
......@@ -26,30 +26,102 @@
#ifndef OCFS2_ALLOC_H
#define OCFS2_ALLOC_H
/*
* For xattr tree leaf, we limit the leaf byte size to be 64K.
*/
#define OCFS2_MAX_XATTR_TREE_LEAF_SIZE 65536
/*
* ocfs2_extent_tree and ocfs2_extent_tree_operations are used to abstract
* the b-tree operations in ocfs2. Now all the b-tree operations are not
* limited to ocfs2_dinode only. Any data which need to allocate clusters
* to store can use b-tree. And it only needs to implement its ocfs2_extent_tree
* and operation.
*
* ocfs2_extent_tree becomes the first-class object for extent tree
* manipulation. Callers of the alloc.c code need to fill it via one of
* the ocfs2_init_*_extent_tree() operations below.
*
* ocfs2_extent_tree contains info for the root of the b-tree, it must have a
* root ocfs2_extent_list and a root_bh so that they can be used in the b-tree
* functions.
* ocfs2_extent_tree_operations abstract the normal operations we do for
* the root of extent b-tree.
*/
struct ocfs2_extent_tree_operations;
struct ocfs2_extent_tree {
struct ocfs2_extent_tree_operations *et_ops;
struct buffer_head *et_root_bh;
struct ocfs2_extent_list *et_root_el;
void *et_object;
unsigned int et_max_leaf_clusters;
};
/*
* ocfs2_init_*_extent_tree() will fill an ocfs2_extent_tree from the
* specified object buffer.
*/
void ocfs2_init_dinode_extent_tree(struct ocfs2_extent_tree *et,
struct inode *inode,
struct buffer_head *bh);
void ocfs2_init_xattr_tree_extent_tree(struct ocfs2_extent_tree *et,
struct inode *inode,
struct buffer_head *bh);
void ocfs2_init_xattr_value_extent_tree(struct ocfs2_extent_tree *et,
struct inode *inode,
struct buffer_head *bh,
struct ocfs2_xattr_value_root *xv);
struct ocfs2_alloc_context;
int ocfs2_insert_extent(struct ocfs2_super *osb,
handle_t *handle,
struct inode *inode,
struct buffer_head *fe_bh,
struct ocfs2_extent_tree *et,
u32 cpos,
u64 start_blk,
u32 new_clusters,
u8 flags,
struct ocfs2_alloc_context *meta_ac);
enum ocfs2_alloc_restarted {
RESTART_NONE = 0,
RESTART_TRANS,
RESTART_META
};
int ocfs2_add_clusters_in_btree(struct ocfs2_super *osb,
struct inode *inode,
u32 *logical_offset,
u32 clusters_to_add,
int mark_unwritten,
struct ocfs2_extent_tree *et,
handle_t *handle,
struct ocfs2_alloc_context *data_ac,
struct ocfs2_alloc_context *meta_ac,
enum ocfs2_alloc_restarted *reason_ret);
struct ocfs2_cached_dealloc_ctxt;
int ocfs2_mark_extent_written(struct inode *inode, struct buffer_head *di_bh,
int ocfs2_mark_extent_written(struct inode *inode,
struct ocfs2_extent_tree *et,
handle_t *handle, u32 cpos, u32 len, u32 phys,
struct ocfs2_alloc_context *meta_ac,
struct ocfs2_cached_dealloc_ctxt *dealloc);
int ocfs2_remove_extent(struct inode *inode, struct buffer_head *di_bh,
int ocfs2_remove_extent(struct inode *inode,
struct ocfs2_extent_tree *et,
u32 cpos, u32 len, handle_t *handle,
struct ocfs2_alloc_context *meta_ac,
struct ocfs2_cached_dealloc_ctxt *dealloc);
int ocfs2_num_free_extents(struct ocfs2_super *osb,
struct inode *inode,
struct ocfs2_dinode *fe);
/* how many new metadata chunks would an allocation need at maximum? */
static inline int ocfs2_extend_meta_needed(struct ocfs2_dinode *fe)
struct ocfs2_extent_tree *et);
/*
* how many new metadata chunks would an allocation need at maximum?
*
* Please note that the caller must make sure that root_el is the root
* of extent tree. So for an inode, it should be &fe->id2.i_list. Otherwise
* the result may be wrong.
*/
static inline int ocfs2_extend_meta_needed(struct ocfs2_extent_list *root_el)
{
/*
* Rather than do all the work of determining how much we need
......@@ -59,7 +131,7 @@ static inline int ocfs2_extend_meta_needed(struct ocfs2_dinode *fe)
* new tree_depth==0 extent_block, and one block at the new
* top-of-the tree.
*/
return le16_to_cpu(fe->id2.i_list.l_tree_depth) + 2;
return le16_to_cpu(root_el->l_tree_depth) + 2;
}
void ocfs2_dinode_new_extent_list(struct inode *inode, struct ocfs2_dinode *di);
......
......@@ -68,9 +68,7 @@ static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
goto bail;
}
status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
OCFS2_I(inode)->ip_blkno,
&bh, OCFS2_BH_CACHED, inode);
status = ocfs2_read_block(inode, OCFS2_I(inode)->ip_blkno, &bh);
if (status < 0) {
mlog_errno(status);
goto bail;
......@@ -128,8 +126,7 @@ static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
err = 0;
bail:
if (bh)
brelse(bh);
brelse(bh);
mlog_exit(err);
return err;
......@@ -261,13 +258,11 @@ static int ocfs2_readpage_inline(struct inode *inode, struct page *page)
{
int ret;
struct buffer_head *di_bh = NULL;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
BUG_ON(!PageLocked(page));
BUG_ON(!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL));
ret = ocfs2_read_block(osb, OCFS2_I(inode)->ip_blkno, &di_bh,
OCFS2_BH_CACHED, inode);
ret = ocfs2_read_block(inode, OCFS2_I(inode)->ip_blkno, &di_bh);
if (ret) {
mlog_errno(ret);
goto out;
......@@ -485,11 +480,14 @@ handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
}
if (ocfs2_should_order_data(inode)) {
ret = ocfs2_jbd2_file_inode(handle, inode);
#ifdef CONFIG_OCFS2_COMPAT_JBD
ret = walk_page_buffers(handle,
page_buffers(page),
from, to, NULL,
ocfs2_journal_dirty_data);
if (ret < 0)
#endif
if (ret < 0)
mlog_errno(ret);
}
out:
......@@ -669,7 +667,7 @@ static void ocfs2_invalidatepage(struct page *page, unsigned long offset)
{
journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
journal_invalidatepage(journal, page, offset);
jbd2_journal_invalidatepage(journal, page, offset);
}
static int ocfs2_releasepage(struct page *page, gfp_t wait)
......@@ -678,7 +676,7 @@ static int ocfs2_releasepage(struct page *page, gfp_t wait)
if (!page_has_buffers(page))
return 0;
return journal_try_to_free_buffers(journal, page, wait);
return jbd2_journal_try_to_free_buffers(journal, page, wait);
}
static ssize_t ocfs2_direct_IO(int rw,
......@@ -1074,11 +1072,15 @@ static void ocfs2_write_failure(struct inode *inode,
tmppage = wc->w_pages[i];
if (page_has_buffers(tmppage)) {
if (ocfs2_should_order_data(inode))
if (ocfs2_should_order_data(inode)) {
ocfs2_jbd2_file_inode(wc->w_handle, inode);
#ifdef CONFIG_OCFS2_COMPAT_JBD
walk_page_buffers(wc->w_handle,
page_buffers(tmppage),
from, to, NULL,
ocfs2_journal_dirty_data);
#endif
}
block_commit_write(tmppage, from, to);
}
......@@ -1242,6 +1244,7 @@ static int ocfs2_write_cluster(struct address_space *mapping,
int ret, i, new, should_zero = 0;
u64 v_blkno, p_blkno;
struct inode *inode = mapping->host;
struct ocfs2_extent_tree et;
new = phys == 0 ? 1 : 0;
if (new || unwritten)
......@@ -1255,10 +1258,10 @@ static int ocfs2_write_cluster(struct address_space *mapping,
* any additional semaphores or cluster locks.
*/
tmp_pos = cpos;
ret = ocfs2_do_extend_allocation(OCFS2_SB(inode->i_sb), inode,
&tmp_pos, 1, 0, wc->w_di_bh,
wc->w_handle, data_ac,
meta_ac, NULL);
ret = ocfs2_add_inode_data(OCFS2_SB(inode->i_sb), inode,
&tmp_pos, 1, 0, wc->w_di_bh,
wc->w_handle, data_ac,
meta_ac, NULL);
/*
* This shouldn't happen because we must have already
* calculated the correct meta data allocation required. The
......@@ -1276,7 +1279,8 @@ static int ocfs2_write_cluster(struct address_space *mapping,
goto out;
}
} else if (unwritten) {
ret = ocfs2_mark_extent_written(inode, wc->w_di_bh,
ocfs2_init_dinode_extent_tree(&et, inode, wc->w_di_bh);
ret = ocfs2_mark_extent_written(inode, &et,
wc->w_handle, cpos, 1, phys,
meta_ac, &wc->w_dealloc);
if (ret < 0) {
......@@ -1665,6 +1669,7 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
struct ocfs2_alloc_context *data_ac = NULL;
struct ocfs2_alloc_context *meta_ac = NULL;
handle_t *handle;
struct ocfs2_extent_tree et;
ret = ocfs2_alloc_write_ctxt(&wc, osb, pos, len, di_bh);
if (ret) {
......@@ -1712,14 +1717,23 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
* ocfs2_lock_allocators(). It greatly over-estimates
* the work to be done.
*/
ret = ocfs2_lock_allocators(inode, di, clusters_to_alloc,
extents_to_split, &data_ac, &meta_ac);
mlog(0, "extend inode %llu, i_size = %lld, di->i_clusters = %u,"
" clusters_to_add = %u, extents_to_split = %u\n",
(unsigned long long)OCFS2_I(inode)->ip_blkno,
(long long)i_size_read(inode), le32_to_cpu(di->i_clusters),
clusters_to_alloc, extents_to_split);
ocfs2_init_dinode_extent_tree(&et, inode, wc->w_di_bh);
ret = ocfs2_lock_allocators(inode, &et,
clusters_to_alloc, extents_to_split,
&data_ac, &meta_ac);
if (ret) {
mlog_errno(ret);
goto out;
}
credits = ocfs2_calc_extend_credits(inode->i_sb, di,
credits = ocfs2_calc_extend_credits(inode->i_sb,
&di->id2.i_list,
clusters_to_alloc);
}
......@@ -1905,11 +1919,15 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
}
if (page_has_buffers(tmppage)) {
if (ocfs2_should_order_data(inode))
if (ocfs2_should_order_data(inode)) {
ocfs2_jbd2_file_inode(wc->w_handle, inode);
#ifdef CONFIG_OCFS2_COMPAT_JBD
walk_page_buffers(wc->w_handle,
page_buffers(tmppage),
from, to, NULL,
ocfs2_journal_dirty_data);
#endif
}
block_commit_write(tmppage, from, to);
}
}
......
......@@ -66,7 +66,7 @@ int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
/* remove from dirty list before I/O. */
clear_buffer_dirty(bh);
get_bh(bh); /* for end_buffer_write_sync() */
get_bh(bh); /* for end_buffer_write_sync() */
bh->b_end_io = end_buffer_write_sync;
submit_bh(WRITE, bh);
......@@ -88,22 +88,103 @@ out:
return ret;
}
int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr,
struct buffer_head *bhs[], int flags,
struct inode *inode)
int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
unsigned int nr, struct buffer_head *bhs[])
{
int status = 0;
unsigned int i;
struct buffer_head *bh;
if (!nr) {
mlog(ML_BH_IO, "No buffers will be read!\n");
goto bail;
}
for (i = 0 ; i < nr ; i++) {
if (bhs[i] == NULL) {
bhs[i] = sb_getblk(osb->sb, block++);
if (bhs[i] == NULL) {
status = -EIO;
mlog_errno(status);
goto bail;
}
}
bh = bhs[i];
if (buffer_jbd(bh)) {
mlog(ML_ERROR,
"trying to sync read a jbd "
"managed bh (blocknr = %llu), skipping\n",
(unsigned long long)bh->b_blocknr);
continue;
}
if (buffer_dirty(bh)) {
/* This should probably be a BUG, or
* at least return an error. */
mlog(ML_ERROR,
"trying to sync read a dirty "
"buffer! (blocknr = %llu), skipping\n",
(unsigned long long)bh->b_blocknr);
continue;
}
lock_buffer(bh);
if (buffer_jbd(bh)) {
mlog(ML_ERROR,
"block %llu had the JBD bit set "
"while I was in lock_buffer!",
(unsigned long long)bh->b_blocknr);
BUG();
}
clear_buffer_uptodate(bh);
get_bh(bh); /* for end_buffer_read_sync() */
bh->b_end_io = end_buffer_read_sync;
submit_bh(READ, bh);
}
for (i = nr; i > 0; i--) {
bh = bhs[i - 1];
if (buffer_jbd(bh)) {
mlog(ML_ERROR,
"the journal got the buffer while it was "
"locked for io! (blocknr = %llu)\n",
(unsigned long long)bh->b_blocknr);
BUG();
}
wait_on_buffer(bh);
if (!buffer_uptodate(bh)) {
/* Status won't be cleared from here on out,
* so we can safely record this and loop back
* to cleanup the other buffers. */
status = -EIO;
put_bh(bh);
bhs[i - 1] = NULL;
}
}
bail:
return status;
}
int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
struct buffer_head *bhs[], int flags)
{
int status = 0;
struct super_block *sb;
int i, ignore_cache = 0;
struct buffer_head *bh;
mlog_entry("(block=(%llu), nr=(%d), flags=%d, inode=%p)\n",
(unsigned long long)block, nr, flags, inode);
mlog_entry("(inode=%p, block=(%llu), nr=(%d), flags=%d)\n",
inode, (unsigned long long)block, nr, flags);
BUG_ON(!inode);
BUG_ON((flags & OCFS2_BH_READAHEAD) &&
(!inode || !(flags & OCFS2_BH_CACHED)));
(flags & OCFS2_BH_IGNORE_CACHE));
if (osb == NULL || osb->sb == NULL || bhs == NULL) {
if (bhs == NULL) {
status = -EINVAL;
mlog_errno(status);
goto bail;
......@@ -122,26 +203,19 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr,
goto bail;
}
sb = osb->sb;
if (flags & OCFS2_BH_CACHED && !inode)
flags &= ~OCFS2_BH_CACHED;
if (inode)
mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
for (i = 0 ; i < nr ; i++) {
if (bhs[i] == NULL) {
bhs[i] = sb_getblk(sb, block++);
bhs[i] = sb_getblk(inode->i_sb, block++);
if (bhs[i] == NULL) {
if (inode)
mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
status = -EIO;
mlog_errno(status);
goto bail;
}
}
bh = bhs[i];
ignore_cache = 0;
ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
/* There are three read-ahead cases here which we need to
* be concerned with. All three assume a buffer has
......@@ -167,26 +241,27 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr,
* before our is-it-in-flight check.
*/
if (flags & OCFS2_BH_CACHED &&
!ocfs2_buffer_uptodate(inode, bh)) {
if (!ignore_cache && !ocfs2_buffer_uptodate(inode, bh)) {
mlog(ML_UPTODATE,
"bh (%llu), inode %llu not uptodate\n",
(unsigned long long)bh->b_blocknr,
(unsigned long long)OCFS2_I(inode)->ip_blkno);
/* We're using ignore_cache here to say
* "go to disk" */
ignore_cache = 1;
}
/* XXX: Can we ever get this and *not* have the cached
* flag set? */
if (buffer_jbd(bh)) {
if (!(flags & OCFS2_BH_CACHED) || ignore_cache)
if (ignore_cache)
mlog(ML_BH_IO, "trying to sync read a jbd "
"managed bh (blocknr = %llu)\n",
(unsigned long long)bh->b_blocknr);
continue;
}
if (!(flags & OCFS2_BH_CACHED) || ignore_cache) {
if (ignore_cache) {
if (buffer_dirty(bh)) {
/* This should probably be a BUG, or
* at least return an error. */
......@@ -221,7 +296,7 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr,
* previously read-ahead buffer may have
* completed I/O while we were waiting for the
* buffer lock. */
if ((flags & OCFS2_BH_CACHED)
if (!(flags & OCFS2_BH_IGNORE_CACHE)
&& !(flags & OCFS2_BH_READAHEAD)
&& ocfs2_buffer_uptodate(inode, bh)) {
unlock_buffer(bh);
......@@ -265,15 +340,14 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr,
/* Always set the buffer in the cache, even if it was
* a forced read, or read-ahead which hasn't yet
* completed. */
if (inode)
ocfs2_set_buffer_uptodate(inode, bh);
ocfs2_set_buffer_uptodate(inode, bh);
}
if (inode)
mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n",
(unsigned long long)block, nr,
(!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes", flags);
((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes",
flags);
bail:
......
......@@ -31,31 +31,29 @@
void ocfs2_end_buffer_io_sync(struct buffer_head *bh,
int uptodate);
static inline int ocfs2_read_block(struct ocfs2_super *osb,
static inline int ocfs2_read_block(struct inode *inode,
u64 off,
struct buffer_head **bh,
int flags,
struct inode *inode);
struct buffer_head **bh);
int ocfs2_write_block(struct ocfs2_super *osb,
struct buffer_head *bh,
struct inode *inode);
int ocfs2_read_blocks(struct ocfs2_super *osb,
int ocfs2_read_blocks(struct inode *inode,
u64 block,
int nr,
struct buffer_head *bhs[],
int flags,
struct inode *inode);
int flags);
int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
unsigned int nr, struct buffer_head *bhs[]);
int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
struct buffer_head *bh);
#define OCFS2_BH_CACHED 1
#define OCFS2_BH_IGNORE_CACHE 1
#define OCFS2_BH_READAHEAD 8
static inline int ocfs2_read_block(struct ocfs2_super * osb, u64 off,
struct buffer_head **bh, int flags,
struct inode *inode)