[RFC PATCH -v2 1/9] ext4: sparse fixes

[RFC PATCH -v2 1/9] ext4: sparse fixes

[Aneesh Kumar K.V]

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/ext4.h    |    3 +++
 fs/ext4/extents.c |    4 ++--
 fs/ext4/inode.c   |    2 +-
 fs/ext4/mballoc.c |    4 +++-
 fs/ext4/super.c   |    4 ++--
 5 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0d65757..fee616d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1350,6 +1350,9 @@ extern int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode,
 			sector_t block, unsigned long 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);
+
 #endif	/* __KERNEL__ */
 
 #endif	/* _EXT4_H */
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index a17f53c..400b9c4 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3115,7 +3115,7 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
 /*
  * Callback function called for each extent to gather FIEMAP information.
  */
-int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
+static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
 		       struct ext4_ext_cache *newex, struct ext4_extent *ex,
 		       void *data)
 {
@@ -3184,7 +3184,7 @@ int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
 /* fiemap flags we can handle specified here */
 #define EXT4_FIEMAP_FLAGS	(FIEMAP_FLAG_SYNC|FIEMAP_FLAG_XATTR)
 
-int ext4_xattr_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo)
+static int ext4_xattr_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo)
 {
 	__u64 physical = 0;
 	__u64 length;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8dbf695..2d070ef 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3841,7 +3841,7 @@ static int __ext4_get_inode_loc(struct inode *inode,
 	ext4_fsblk_t		block;
 	int			inodes_per_block, inode_offset;
 
-	iloc->bh = 0;
+	iloc->bh = NULL;
 	if (!ext4_valid_inum(sb, inode->i_ino))
 		return -EIO;
 
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 0643f9c..20c8b09 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1056,6 +1056,8 @@ static void mb_set_bits(spinlock_t *lock, void *bm, int cur, int len)
 
 static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
 			  int first, int count)
+__releases(bitlock)
+__acquires(bitlock)
 {
 	int block = 0;
 	int max = 0;
@@ -2246,7 +2248,7 @@ ext4_mb_store_history(struct ext4_allocation_context *ac)
 
 
 /* Create and initialize ext4_group_info data for the given group. */
-int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
+static int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
 			  struct ext4_group_desc *desc)
 {
 	int i, len;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5bfc235..133da2e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2022,8 +2022,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		       sb->s_id, le32_to_cpu(features));
 		goto failed_mount;
 	}
-	has_huge_files = EXT4_HAS_RO_COMPAT_FEATURE(sb,
-				    EXT4_FEATURE_RO_COMPAT_HUGE_FILE);
+	has_huge_files = le32_to_cpu(EXT4_HAS_RO_COMPAT_FEATURE(sb,
+				    EXT4_FEATURE_RO_COMPAT_HUGE_FILE));
 	if (has_huge_files) {
 		/*
 		 * Large file size enabled file system can only be
-- 
1.6.0.3.514.g2f91b

[RFC PATCH -v2 2/9] ext4: Add blocks added during resize to bitmap

[Aneesh Kumar K.V]

With this change new blocks added during resize
are marked as free in the block bitmap and the
group is flagged with EXT4_GROUP_INFO_NEED_INIT_BIT
flag. This make sure when mballoc tries to allocate
blocks from the new group we would reload the
buddy information using the bitmap present in the disk.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/balloc.c |  136 ++++++++++++------------------------------------------
 fs/ext4/ext4.h   |    5 +-
 fs/ext4/resize.c |   11 +----
 3 files changed, 34 insertions(+), 118 deletions(-)

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 4397274..d598fd6 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -20,6 +20,7 @@
 #include "ext4.h"
 #include "ext4_jbd2.h"
 #include "group.h"
+#include "mballoc.h"
 
 /*
  * balloc.c contains the blocks allocation and deallocation routines
@@ -350,62 +351,43 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 }
 
 /**
- * ext4_free_blocks_sb() -- Free given blocks and update quota
+ * ext4_add_groupblocks() -- Add given blocks to an existing group
  * @handle:			handle to this transaction
  * @sb:				super block
- * @block:			start physcial block to free
+ * @block:			start physcial block to add to the block group
  * @count:			number of blocks to free
- * @pdquot_freed_blocks:	pointer to quota
  *
- * XXX This function is only used by the on-line resizing code, which
- * should probably be fixed up to call the mballoc variant.  There
- * this needs to be cleaned up later; in fact, I'm not convinced this
- * is 100% correct in the face of the mballoc code.  The online resizing
- * code needs to be fixed up to more tightly (and correctly) interlock
- * with the mballoc code.
+ * This marks the blocks as free in the bitmap. We ask the
+ * mballoc to reload the buddy after this by setting group
+ * EXT4_GROUP_INFO_NEED_INIT_BIT flag
  */
-void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
-			 ext4_fsblk_t block, unsigned long count,
-			 unsigned long *pdquot_freed_blocks)
+void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
+			 ext4_fsblk_t block, unsigned long count)
 {
 	struct buffer_head *bitmap_bh = NULL;
 	struct buffer_head *gd_bh;
 	ext4_group_t block_group;
 	ext4_grpblk_t bit;
 	unsigned long i;
-	unsigned long overflow;
 	struct ext4_group_desc *desc;
 	struct ext4_super_block *es;
 	struct ext4_sb_info *sbi;
 	int err = 0, ret;
-	ext4_grpblk_t group_freed;
+	ext4_grpblk_t blocks_freed;
+	struct ext4_group_info *grp;
 
-	*pdquot_freed_blocks = 0;
 	sbi = EXT4_SB(sb);
 	es = sbi->s_es;
-	if (block < le32_to_cpu(es->s_first_data_block) ||
-	    block + count < block ||
-	    block + count > ext4_blocks_count(es)) {
-		ext4_error(sb, "ext4_free_blocks",
-			   "Freeing blocks not in datazone - "
-			   "block = %llu, count = %lu", block, count);
-		goto error_return;
-	}
-
-	ext4_debug("freeing block(s) %llu-%llu\n", block, block + count - 1);
+	ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
 
-do_more:
-	overflow = 0;
 	ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
 	/*
 	 * Check to see if we are freeing blocks across a group
 	 * boundary.
 	 */
 	if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
-		overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
-		count -= overflow;
+		goto error_return;
 	}
-	brelse(bitmap_bh);
 	bitmap_bh = ext4_read_block_bitmap(sb, block_group);
 	if (!bitmap_bh)
 		goto error_return;
@@ -418,18 +400,17 @@ void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
 	    in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
 	    in_range(block + count - 1, ext4_inode_table(sb, desc),
 		     sbi->s_itb_per_group)) {
-		ext4_error(sb, "ext4_free_blocks",
-			   "Freeing blocks in system zones - "
+		ext4_error(sb, __func__,
+			   "Adding blocks in system zones - "
 			   "Block = %llu, count = %lu",
 			   block, count);
 		goto error_return;
 	}
 
 	/*
-	 * We are about to start releasing blocks in the bitmap,
+	 * We are about to add blocks to the bitmap,
 	 * so we need undo access.
 	 */
-	/* @@@ check errors */
 	BUFFER_TRACE(bitmap_bh, "getting undo access");
 	err = ext4_journal_get_undo_access(handle, bitmap_bh);
 	if (err)
@@ -445,87 +426,28 @@ void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
 	if (err)
 		goto error_return;
 
-	jbd_lock_bh_state(bitmap_bh);
-
-	for (i = 0, group_freed = 0; i < count; i++) {
-		/*
-		 * An HJ special.  This is expensive...
-		 */
-#ifdef CONFIG_JBD2_DEBUG
-		jbd_unlock_bh_state(bitmap_bh);
-		{
-			struct buffer_head *debug_bh;
-			debug_bh = sb_find_get_block(sb, block + i);
-			if (debug_bh) {
-				BUFFER_TRACE(debug_bh, "Deleted!");
-				if (!bh2jh(bitmap_bh)->b_committed_data)
-					BUFFER_TRACE(debug_bh,
-						"No commited data in bitmap");
-				BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
-				__brelse(debug_bh);
-			}
-		}
-		jbd_lock_bh_state(bitmap_bh);
-#endif
-		if (need_resched()) {
-			jbd_unlock_bh_state(bitmap_bh);
-			cond_resched();
-			jbd_lock_bh_state(bitmap_bh);
-		}
-		/* @@@ This prevents newly-allocated data from being
-		 * freed and then reallocated within the same
-		 * transaction.
-		 *
-		 * Ideally we would want to allow that to happen, but to
-		 * do so requires making jbd2_journal_forget() capable of
-		 * revoking the queued write of a data block, which
-		 * implies blocking on the journal lock.  *forget()
-		 * cannot block due to truncate races.
-		 *
-		 * Eventually we can fix this by making jbd2_journal_forget()
-		 * return a status indicating whether or not it was able
-		 * to revoke the buffer.  On successful revoke, it is
-		 * safe not to set the allocation bit in the committed
-		 * bitmap, because we know that there is no outstanding
-		 * activity on the buffer any more and so it is safe to
-		 * reallocate it.
-		 */
-		BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
-		J_ASSERT_BH(bitmap_bh,
-				bh2jh(bitmap_bh)->b_committed_data != NULL);
-		ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
-				bh2jh(bitmap_bh)->b_committed_data);
-
-		/*
-		 * We clear the bit in the bitmap after setting the committed
-		 * data bit, because this is the reverse order to that which
-		 * the allocator uses.
-		 */
+	for (i = 0, blocks_freed = 0; i < count; i++) {
 		BUFFER_TRACE(bitmap_bh, "clear bit");
 		if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 						bit + i, bitmap_bh->b_data)) {
-			jbd_unlock_bh_state(bitmap_bh);
 			ext4_error(sb, __func__,
 				   "bit already cleared for block %llu",
 				   (ext4_fsblk_t)(block + i));
-			jbd_lock_bh_state(bitmap_bh);
 			BUFFER_TRACE(bitmap_bh, "bit already cleared");
 		} else {
-			group_freed++;
+			blocks_freed++;
 		}
 	}
-	jbd_unlock_bh_state(bitmap_bh);
-
 	spin_lock(sb_bgl_lock(sbi, block_group));
-	le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
+	le16_add_cpu(&desc->bg_free_blocks_count, blocks_freed);
 	desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
 	spin_unlock(sb_bgl_lock(sbi, block_group));
-	percpu_counter_add(&sbi->s_freeblocks_counter, count);
+	percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
 
 	if (sbi->s_log_groups_per_flex) {
 		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
 		spin_lock(sb_bgl_lock(sbi, flex_group));
-		sbi->s_flex_groups[flex_group].free_blocks += count;
+		sbi->s_flex_groups[flex_group].free_blocks += blocks_freed;
 		spin_unlock(sb_bgl_lock(sbi, flex_group));
 	}
 
@@ -536,15 +458,17 @@ void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
 	/* And the group descriptor block */
 	BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 	ret = ext4_journal_dirty_metadata(handle, gd_bh);
-	if (!err) err = ret;
-	*pdquot_freed_blocks += group_freed;
-
-	if (overflow && !err) {
-		block += count;
-		count = overflow;
-		goto do_more;
-	}
+	if (!err)
+		err = ret;
 	sb->s_dirt = 1;
+	/*
+	 * request to reload the buddy with the
+	 * new bitmap information
+	 */
+	grp = ext4_get_group_info(sb, block_group);
+	set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
+	ext4_mb_update_group_info(grp, blocks_freed);
+
 error_return:
 	brelse(bitmap_bh);
 	ext4_std_error(sb, err);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index fee616d..004dd25 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1062,9 +1062,8 @@ extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
 extern int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
 extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
 			ext4_fsblk_t block, unsigned long count, int metadata);
-extern void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
-				ext4_fsblk_t block, unsigned long count,
-				unsigned long *pdquot_freed_blocks);
+extern void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
+				ext4_fsblk_t block, unsigned long count);
 extern ext4_fsblk_t ext4_count_free_blocks(struct super_block *);
 extern void ext4_check_blocks_bitmap(struct super_block *);
 extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index b6ec184..ecaacbb 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -975,9 +975,7 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 	struct buffer_head *bh;
 	handle_t *handle;
 	int err;
-	unsigned long freed_blocks;
 	ext4_group_t group;
-	struct ext4_group_info *grp;
 
 	/* We don't need to worry about locking wrt other resizers just
 	 * yet: we're going to revalidate es->s_blocks_count after
@@ -1076,7 +1074,8 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 	unlock_super(sb);
 	ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
 		   o_blocks_count + add);
-	ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
+	/* We add the blocks to the bitmap and set the group need init bit */
+	ext4_add_groupblocks(handle, sb, o_blocks_count, add);
 	ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
 		   o_blocks_count + add);
 	if ((err = ext4_journal_stop(handle)))
@@ -1119,12 +1118,6 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 			ClearPageUptodate(page);
 			page_cache_release(page);
 		}
-
-		/* Get the info on the last group */
-		grp = ext4_get_group_info(sb, group);

[RFC PATCH -v2 3/9] ext4: Use EXT4_GROUP_INFO_NEED_INIT_BIT during resize

[Aneesh Kumar K.V]

The new groups added during resize are flagged as
need_init group. Make sure we properly initialize these
groups. When we have block size < page size and we are adding
new groups the page may still be marked uptodate even though
we haven't initialized the group.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/balloc.c  |   21 +++--
 fs/ext4/ext4.h    |    2 +-
 fs/ext4/mballoc.c |  218 ++++++++++++++++++++++++++++++++++++++---------------
 fs/ext4/mballoc.h |    3 +
 fs/ext4/resize.c  |   41 +----------
 5 files changed, 176 insertions(+), 109 deletions(-)

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index d598fd6..07266ec 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -381,6 +381,7 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 	ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
 
 	ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
+	grp = ext4_get_group_info(sb, block_group);
 	/*
 	 * Check to see if we are freeing blocks across a group
 	 * boundary.
@@ -425,7 +426,11 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 	err = ext4_journal_get_write_access(handle, gd_bh);
 	if (err)
 		goto error_return;
-
+	/*
+	 * make sure we don't allow a parallel init on other groups in the
+	 * same buddy cache
+	 */
+	down_write(&grp->alloc_sem);
 	for (i = 0, blocks_freed = 0; i < count; i++) {
 		BUFFER_TRACE(bitmap_bh, "clear bit");
 		if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
@@ -450,6 +455,13 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 		sbi->s_flex_groups[flex_group].free_blocks += blocks_freed;
 		spin_unlock(sb_bgl_lock(sbi, flex_group));
 	}
+	/*
+	 * request to reload the buddy with the
+	 * new bitmap information
+	 */
+	set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
+	ext4_mb_update_group_info(grp, blocks_freed);
+	up_write(&grp->alloc_sem);
 
 	/* We dirtied the bitmap block */
 	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
@@ -461,13 +473,6 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 	if (!err)
 		err = ret;
 	sb->s_dirt = 1;
-	/*
-	 * request to reload the buddy with the
-	 * new bitmap information
-	 */
-	grp = ext4_get_group_info(sb, block_group);
-	set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
-	ext4_mb_update_group_info(grp, blocks_freed);
 
 error_return:
 	brelse(bitmap_bh);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 004dd25..89c7426 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1109,7 +1109,7 @@ extern int __init init_ext4_mballoc(void);
 extern void exit_ext4_mballoc(void);
 extern void ext4_mb_free_blocks(handle_t *, struct inode *,
 		unsigned long, unsigned long, int, unsigned long *);
-extern int ext4_mb_add_more_groupinfo(struct super_block *sb,
+extern int ext4_mb_add_groupinfo(struct super_block *sb,
 		ext4_group_t i, struct ext4_group_desc *desc);
 extern void ext4_mb_update_group_info(struct ext4_group_info *grp,
 		ext4_grpblk_t add);
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 20c8b09..05631d1 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -886,18 +886,20 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
 ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 					struct ext4_buddy *e4b)
 {
-	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	struct inode *inode = sbi->s_buddy_cache;
 	int blocks_per_page;
 	int block;
 	int pnum;
 	int poff;
 	struct page *page;
 	int ret;
+	struct ext4_group_info *grp;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	struct inode *inode = sbi->s_buddy_cache;
 
 	mb_debug("load group %lu\n", group);
 
 	blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
+	grp = ext4_get_group_info(sb, group);
 
 	e4b->bd_blkbits = sb->s_blocksize_bits;
 	e4b->bd_info = ext4_get_group_info(sb, group);
@@ -905,6 +907,15 @@ ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 	e4b->bd_group = group;
 	e4b->bd_buddy_page = NULL;
 	e4b->bd_bitmap_page = NULL;
+	e4b->alloc_semp = &grp->alloc_sem;
+
+	/* Take the read lock on the group alloc
+	 * sem. This would make sure a parallel
+	 * ext4_mb_init_group happening on other
+	 * groups mapped by the page is blocked
+	 * till we are done with allocation
+	 */
+	down_read(e4b->alloc_semp);
 
 	/*
 	 * the buddy cache inode stores the block bitmap
@@ -919,8 +930,15 @@ ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 	 * what we'd like to avoid in fast path ... */
 	page = find_get_page(inode->i_mapping, pnum);
 	if (page == NULL || !PageUptodate(page)) {
-		if (page)
+		if (page) {
+			/* If the page is not uptodate
+			 * that would imply nobody is using
+			 * it. So we should be able to drop
+			 * page_cache without being worried
+			 * about other group allocation
+			 */
 			page_cache_release(page);
+		}
 		page = find_or_create_page(inode->i_mapping, pnum, GFP_NOFS);
 		if (page) {
 			BUG_ON(page->mapping != inode->i_mapping);
@@ -985,6 +1003,9 @@ ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 		page_cache_release(e4b->bd_buddy_page);
 	e4b->bd_buddy = NULL;
 	e4b->bd_bitmap = NULL;
+
+	/* Done with the buddy cache */
+	up_read(e4b->alloc_semp);
 	return ret;
 }
 
@@ -994,6 +1015,8 @@ static void ext4_mb_release_desc(struct ext4_buddy *e4b)
 		page_cache_release(e4b->bd_bitmap_page);
 	if (e4b->bd_buddy_page)
 		page_cache_release(e4b->bd_buddy_page);
+	/* Done with the buddy cache */
+	up_read(e4b->alloc_semp);
 }
 
 
@@ -1694,6 +1717,129 @@ static int ext4_mb_good_group(struct ext4_allocation_context *ac,
 	return 0;
 }
 
+static int ext4_mb_init_group(struct super_block *sb, ext4_group_t group)
+{
+
+	int i, ret;
+	void *bitmap;
+	int blocks_per_page;
+	int groups_per_page;
+	int block, pnum, poff;
+	int num_grp_locked = 0;
+	ext4_group_t first_group;
+	struct ext4_group_info *grp, *this_grp;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	struct inode *inode = sbi->s_buddy_cache;
+	struct page *page = NULL, *bitmap_page = NULL;
+
+	mb_debug("init group %lu\n", group);
+	blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
+	/*
+	 * the buddy cache inode stores the block bitmap
+	 * and buddy information in consecutive blocks.
+	 * So for each group we need two blocks.
+	 */
+	block = group * 2;
+	pnum = block / blocks_per_page;
+	poff = block % blocks_per_page;
+	first_group = pnum * blocks_per_page / 2;
+	this_grp = ext4_get_group_info(sb, group);
+
+	groups_per_page = blocks_per_page >> 1;
+	if (groups_per_page == 0)
+		groups_per_page = 1;
+
+	/* read all groups the page covers into the cache */
+	for (i = 0; i < groups_per_page; i++) {
+
+		if ((first_group + i) >= EXT4_SB(sb)->s_groups_count)
+			break;
+		grp = ext4_get_group_info(sb, first_group + i);
+		/* take all groups write allocation
+		 * semaphore. This make sure there is
+		 * no block allocation going on in any
+		 * of that groups
+		 */
+		down_write(&grp->alloc_sem);
+	}
+	/*
+	 * make sure we look at only those groups
+	 * that are locked. A resize can add more
+	 * groups while this happen
+	 */
+	num_grp_locked = i;
+	if (!EXT4_MB_GRP_NEED_INIT(this_grp)) {
+		/*
+		 * somebody initialized the group
+		 * return without doing anything
+		 */
+		ret = 0;
+		goto err;
+	}
+
+	page = find_or_create_page(inode->i_mapping, pnum, GFP_NOFS);
+	if (page) {
+		BUG_ON(page->mapping != inode->i_mapping);
+		ret = ext4_mb_init_cache(page, NULL);
+		if (ret) {
+			unlock_page(page);
+			goto err;
+		}
+		unlock_page(page);
+	}
+	if (page == NULL || !PageUptodate(page)) {
+		ret = -EIO;
+		goto err;
+	}
+	mark_page_accessed(page);
+	bitmap_page = page;
+	bitmap = page_address(page) + (poff * sb->s_blocksize);
+
+	/* init buddy cache */
+	block++;
+	pnum = block / blocks_per_page;
+	poff = block % blocks_per_page;
+	page = find_or_create_page(inode->i_mapping, pnum, GFP_NOFS);
+	if (page == bitmap_page) {
+		/*
+		 * If both the bitmap and buddy are in
+		 * the same page we don't need to force
+		 * init the buddy
+		 */
+		unlock_page(page);
+	} else if (page) {
+		BUG_ON(page->mapping != inode->i_mapping);
+		ret = ext4_mb_init_cache(page, bitmap);
+		if (ret) {
+			unlock_page(page);
+			goto err;
+		}
+		unlock_page(page);
+	}
+	if (page == NULL || !PageUptodate(page)) {
+		ret = -EIO;
+		goto err;
+	}
+	mark_page_accessed(page);
+err:
+	/* release locks on all the groups */
+	for (i = 0; i < num_grp_locked; i++) {
+
+		grp = ext4_get_group_info(sb, first_group + i);
+		/* take all groups write allocation
+		 * semaphore. This make sure there is
+		 * no block allocation going on in any
+		 * of that groups
+		 */
+		up_write(&grp->alloc_sem);
+	}
+	if (bitmap_page)
+		page_cache_release(bitmap_page);
+	if (page)
+		page_cache_release(page);
+	return ret;
+}
+
 static noinline_for_stack int
 ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
 {
@@ -1781,7 +1927,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
 				continue;
 
 			/* quick check to skip empty groups */
-			grp = ext4_get_group_info(ac->ac_sb, group);
+			grp = ext4_get_group_info(sb, group);
 			if (grp->bb_free == 0)
 				continue;
 
@@ -1794,10 +1940,9 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
 				 * we need full data about the group
 				 * to make a good selection
 				 */
-				err = ext4_mb_load_buddy(sb, group, &e4b);
+				err = ext4_mb_init_group(sb, group);
 				if (err)
 					goto out;
-				ext4_mb_release_desc(&e4b);
 			}
 
 			/*
@@ -2248,7 +2393,7 @@ ext4_mb_store_history(struct ext4_allocation_context *ac)
 
 
 /* Create and initialize ext4_group_info data for the given group. */
-static int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
+int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
 			  struct ext4_group_desc *desc)
 {
 	int i, len;
@@ -2306,6 +2451,7 @@ static int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
 	}
 
 	INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list);
+	init_rwsem(&meta_group_info[i]->alloc_sem);
 	meta_group_info[i]->bb_free_root.rb_node = NULL;;
 
 #ifdef DOUBLE_CHECK
@@ -2333,54 +2479,6 @@ static int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
 } /* ext4_mb_add_groupinfo */
 
 /*
- * Add a group to the existing groups.
- * This function is used for online resize
- */
-int ext4_mb_add_more_groupinfo(struct super_block *sb, ext4_group_t group,
-			       struct ext4_group_desc *desc)
-{
-	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	struct inode *inode = sbi->s_buddy_cache;
-	int blocks_per_page;
-	int block;
-	int pnum;
-	struct page *page;
-	int err;
-
-	/* Add group based on group descriptor*/
-	err = ext4_mb_add_groupinfo(sb, group, desc);
-	if (err)
-		return err;
-
-	/*
-	 * Cache pages containing dynamic mb_alloc datas (buddy and bitmap
-	 * datas) are set not up to date so that they will be re-initilaized
-	 * during the next call to ext4_mb_load_buddy
-	 */
-
-	/* Set buddy page as not up to date */
-	blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
-	block = group * 2;
-	pnum = block / blocks_per_page;
-	page = find_get_page(inode->i_mapping, pnum);
-	if (page != NULL) {
-		ClearPageUptodate(page);
-		page_cache_release(page);
-	}
-
-	/* Set bitmap page as not up to date */
-	block++;
-	pnum = block / blocks_per_page;
-	page = find_get_page(inode->i_mapping, pnum);
-	if (page != NULL) {
-		ClearPageUptodate(page);
-		page_cache_release(page);
-	}
-
-	return 0;
-}
-
-/*
  * Update an existing group.
  * This function is used for online resize
  */
@@ -4588,11 +4686,6 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
 	err = ext4_journal_get_write_access(handle, gd_bh);
 	if (err)
 		goto error_return;
-
-	err = ext4_mb_load_buddy(sb, block_group, &e4b);
-	if (err)
-		goto error_return;
-
 #ifdef AGGRESSIVE_CHECK
 	{
 		int i;
@@ -4606,6 +4699,8 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
 	/* We dirtied the bitmap block */
 	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 	err = ext4_journal_dirty_metadata(handle, bitmap_bh);
+	if (err)
+		goto error_return;
 
 	if (ac) {
 		ac->ac_b_ex.fe_group = block_group;
@@ -4614,6 +4709,9 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
 		ext4_mb_store_history(ac);
 	}
 
+	err = ext4_mb_load_buddy(sb, block_group, &e4b);
+	if (err)
+		goto error_return;
 	if (metadata) {
 		/* blocks being freed are metadata. these blocks shouldn't
 		 * be used until this transaction is committed */
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 557308a..7cc69c2 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -20,6 +20,7 @@
 #include <linux/version.h>
 #include <linux/blkdev.h>
 #include <linux/marker.h>
+#include <linux/mutex.h>
 #include "ext4_jbd2.h"
 #include "ext4.h"
 #include "group.h"
@@ -130,6 +131,7 @@ struct ext4_group_info {
 #ifdef DOUBLE_CHECK
 	void		*bb_bitmap;
 #endif
+	struct rw_semaphore alloc_sem;
 	unsigned short	bb_counters[];
 };
 
@@ -251,6 +253,7 @@ struct ext4_buddy {
 	struct super_block *bd_sb;
 	__u16 bd_blkbits;
 	ext4_group_t bd_group;
+	struct rw_semaphore *alloc_semp;
 };
 #define EXT4_MB_BITMAP(e4b)	((e4b)->bd_bitmap)
 #define EXT4_MB_BUDDY(e4b)	((e4b)->bd_buddy)
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index ecaacbb..94ccf24 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -870,7 +870,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 	 * We can allocate memory for mb_alloc based on the new group
 	 * descriptor
 	 */
-	err = ext4_mb_add_more_groupinfo(sb, input->group, gdp);
+	err = ext4_mb_add_groupinfo(sb, input->group, gdp);
 	if (err)
 		goto exit_journal;
 
@@ -1081,45 +1081,6 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 	if ((err = ext4_journal_stop(handle)))
 		goto exit_put;
 
-	/*
-	 * Mark mballoc pages as not up to date so that they will be updated
-	 * next time they are loaded by ext4_mb_load_buddy.
-	 *
-	 * XXX Bad, Bad, BAD!!!  We should not be overloading the
-	 * Uptodate flag, particularly on thte bitmap bh, as way of
-	 * hinting to ext4_mb_load_buddy() that it needs to be
-	 * overloaded.  A user could take a LVM snapshot, then do an
-	 * on-line fsck, and clear the uptodate flag, and this would
-	 * not be a bug in userspace, but a bug in the kernel.  FIXME!!!
-	 */
-	{
-		struct ext4_sb_info *sbi = EXT4_SB(sb);
-		struct inode *inode = sbi->s_buddy_cache;
-		int blocks_per_page;
-		int block;
-		int pnum;
-		struct page *page;
-
-		/* Set buddy page as not up to date */
-		blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
-		block = group * 2;
-		pnum = block / blocks_per_page;
-		page = find_get_page(inode->i_mapping, pnum);
-		if (page != NULL) {
-			ClearPageUptodate(page);
-			page_cache_release(page);
-		}
-
-		/* Set bitmap page as not up to date */
-		block++;
-		pnum = block / blocks_per_page;
-		page = find_get_page(inode->i_mapping, pnum);
-		if (page != NULL) {
-			ClearPageUptodate(page);
-			page_cache_release(page);
-		}
-	}

[RFC PATCH -v2 4/9] ext4: cleanup mballoc header files

[Aneesh Kumar K.V]

Move some of the forward declaration of the static functions
to mballoc.c where they are used. This enables us to include
mballoc.h in other .c files. Also correct the buddy cache
documentation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/mballoc.c |   14 ++++++++++++--
 fs/ext4/mballoc.h |   18 +-----------------
 2 files changed, 13 insertions(+), 19 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 05631d1..390dc81 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -100,7 +100,7 @@
  * inode as:
  *
  *  {                        page                        }
- *  [ group 0 buddy][ group 0 bitmap] [group 1][ group 1]...
+ *  [ group 0 bitmap][ group 0 buddy] [group 1][ group 1]...
  *
  *
  * one block each for bitmap and buddy information.  So for each group we
@@ -330,6 +330,16 @@
  *        object
  *
  */
+static struct kmem_cache *ext4_pspace_cachep;
+static struct kmem_cache *ext4_ac_cachep;
+static struct kmem_cache *ext4_free_ext_cachep;
+static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
+					ext4_group_t group);
+static int ext4_mb_init_per_dev_proc(struct super_block *sb);
+static int ext4_mb_destroy_per_dev_proc(struct super_block *sb);
+static void release_blocks_on_commit(journal_t *journal, transaction_t *txn);
+
+
 
 static inline void *mb_correct_addr_and_bit(int *bit, void *addr)
 {
@@ -716,7 +726,7 @@ static void ext4_mb_generate_buddy(struct super_block *sb,
  * stored in the inode as
  *
  * {                        page                        }
- * [ group 0 buddy][ group 0 bitmap] [group 1][ group 1]...
+ * [ group 0 bitmap][ group 0 buddy] [group 1][ group 1]...
  *
  *
  * one block each for bitmap and buddy information.
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 7cc69c2..407b39a 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -99,9 +99,6 @@
  */
 #define MB_DEFAULT_GROUP_PREALLOC	512
 
-static struct kmem_cache *ext4_pspace_cachep;
-static struct kmem_cache *ext4_ac_cachep;
-static struct kmem_cache *ext4_free_ext_cachep;
 
 struct ext4_free_data {
 	/* this links the free block information from group_info */
@@ -263,25 +260,12 @@ static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 {
 	return;
 }
-#else
-static void ext4_mb_store_history(struct ext4_allocation_context *ac);
 #endif
 
 #define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)
 
 struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
 
-static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
-					ext4_group_t group);
-static void ext4_mb_return_to_preallocation(struct inode *inode,
-					struct ext4_buddy *e4b, sector_t block,
-					int count);
-static void ext4_mb_put_pa(struct ext4_allocation_context *,
-			struct super_block *, struct ext4_prealloc_space *pa);
-static int ext4_mb_init_per_dev_proc(struct super_block *sb);
-static int ext4_mb_destroy_per_dev_proc(struct super_block *sb);
-static void release_blocks_on_commit(journal_t *journal, transaction_t *txn);

[RFC PATCH -v2 5/9] ext4: sparse annotate the group info semaphore

[Aneesh Kumar K.V]

sparse annotate the group info allocation semaphore

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/mballoc.c |   28 +++++++++++++++++++++++-----
 1 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 390dc81..34a365e 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -895,6 +895,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
 static noinline_for_stack int
 ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 					struct ext4_buddy *e4b)
+__acquires(e4b->alloc_semp)
 {
 	int blocks_per_page;
 	int block;
@@ -926,6 +927,7 @@ ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 	 * till we are done with allocation
 	 */
 	down_read(e4b->alloc_semp);
+	__acquire(e4b->alloc_semp);
 
 	/*
 	 * the buddy cache inode stores the block bitmap
@@ -1020,6 +1022,7 @@ ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 }
 
 static void ext4_mb_release_desc(struct ext4_buddy *e4b)
+__releases(e4b->alloc_semp)
 {
 	if (e4b->bd_bitmap_page)
 		page_cache_release(e4b->bd_bitmap_page);
@@ -1027,6 +1030,7 @@ static void ext4_mb_release_desc(struct ext4_buddy *e4b)
 		page_cache_release(e4b->bd_buddy_page);
 	/* Done with the buddy cache */
 	up_read(e4b->alloc_semp);
+	__release(e4b->alloc_semp);
 }
 
 
@@ -1468,8 +1472,10 @@ static int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
 
 	BUG_ON(ex.fe_len <= 0);
 	err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
-	if (err)
+	if (err) {
+		__release(e4b->alloc_semp);
 		return err;
+	}
 
 	ext4_lock_group(ac->ac_sb, group);
 	max = mb_find_extent(e4b, 0, ex.fe_start, ex.fe_len, &ex);
@@ -1499,8 +1505,10 @@ static int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
 		return 0;
 
 	err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
-	if (err)
+	if (err) {
+		__release(e4b->alloc_semp);
 		return err;
+	}
 
 	ext4_lock_group(ac->ac_sb, group);
 	max = mb_find_extent(e4b, 0, ac->ac_g_ex.fe_start,
@@ -1963,8 +1971,10 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
 				continue;
 
 			err = ext4_mb_load_buddy(sb, group, &e4b);
-			if (err)
+			if (err) {
+				__release(e4b->alloc_semp);
 				goto out;
+			}
 
 			ext4_lock_group(sb, group);
 			if (!ext4_mb_good_group(ac, group, cr)) {
@@ -2275,6 +2285,7 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
 		sizeof(struct ext4_group_info);
 	err = ext4_mb_load_buddy(sb, group, &e4b);
 	if (err) {
+		__release(e4b->alloc_semp);
 		seq_printf(seq, "#%-5lu: I/O error\n", group);
 		return 0;
 	}
@@ -3820,6 +3831,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 
 	err = ext4_mb_load_buddy(sb, group, &e4b);
 	if (err) {
+		__release(e4b->alloc_semp);
 		ext4_error(sb, __func__, "Error in loading buddy "
 				"information for %lu\n", group);
 		put_bh(bitmap_bh);
@@ -3987,6 +3999,7 @@ void ext4_discard_preallocations(struct inode *inode)
 
 		err = ext4_mb_load_buddy(sb, group, &e4b);
 		if (err) {
+			__release(e4b->alloc_semp);
 			ext4_error(sb, __func__, "Error in loading buddy "
 					"information for %lu\n", group);
 			continue;
@@ -4260,6 +4273,7 @@ ext4_mb_discard_lg_preallocations(struct super_block *sb,
 
 		ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, NULL);
 		if (ext4_mb_load_buddy(sb, group, &e4b)) {
+			__release(e4b->alloc_semp);
 			ext4_error(sb, __func__, "Error in loading buddy "
 					"information for %lu\n", group);
 			continue;
@@ -4720,8 +4734,10 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
 	}
 
 	err = ext4_mb_load_buddy(sb, block_group, &e4b);
-	if (err)
+	if (err) {
+		__release(e4b->alloc_semp);
 		goto error_return;
+	}
 	if (metadata) {
 		/* blocks being freed are metadata. these blocks shouldn't
 		 * be used until this transaction is committed */
@@ -4805,8 +4821,10 @@ ext4_mb_search_free_extents(struct inode *inode,
 	end = EXT4_BLOCKS_PER_GROUP(sb) - 1;
 
 	err = ext4_mb_load_buddy(sb, group_no, &e4b);
-	if (err)
+	if (err) {
+		__release(e4b->alloc_semp);
 		return err;
+	}
 
 	/* We consider about the boot block if bs = 1k */
 	if (sb->s_blocksize == 1024)
-- 
1.6.0.3.514.g2f91b

[RFC PATCH -v2 6/9] ext4: Call journal commit callback without holding j_list_lock

[Aneesh Kumar K.V]

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/jbd2/checkpoint.c |    2 +-
 fs/jbd2/commit.c     |   13 ++++++++-----
 include/linux/jbd2.h |    4 ++--
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 9203c33..e0c34ae 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -668,6 +668,7 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
 	   safely remove this transaction from the log */
 
 	__jbd2_journal_drop_transaction(journal, transaction);
+	kfree(transaction);
 
 	/* Just in case anybody was waiting for more transactions to be
            checkpointed... */
@@ -742,5 +743,4 @@ void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transact
 	J_ASSERT(journal->j_running_transaction != transaction);
 
 	jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
-	kfree(transaction);
 }
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index ebc667b..4ed9437 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -338,7 +338,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	int space_left = 0;
 	int first_tag = 0;
 	int tag_flag;
-	int i;
+	int i, to_free = 0;
 	int tag_bytes = journal_tag_bytes(journal);
 	struct buffer_head *cbh = NULL; /* For transactional checksums */
 	__u32 crc32_sum = ~0;
@@ -974,12 +974,10 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	journal->j_committing_transaction = NULL;
 	spin_unlock(&journal->j_state_lock);
 
-	if (journal->j_commit_callback)
-		journal->j_commit_callback(journal, commit_transaction);
-
 	if (commit_transaction->t_checkpoint_list == NULL &&
 	    commit_transaction->t_checkpoint_io_list == NULL) {
 		__jbd2_journal_drop_transaction(journal, commit_transaction);
+		to_free = 1;
 	} else {
 		if (journal->j_checkpoint_transactions == NULL) {
 			journal->j_checkpoint_transactions = commit_transaction;
@@ -998,11 +996,16 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	}
 	spin_unlock(&journal->j_list_lock);
 
+	if (journal->j_commit_callback)
+		journal->j_commit_callback(journal, commit_transaction);
+
 	trace_mark(jbd2_end_commit, "dev %s transaction %d head %d",
-		   journal->j_devname, journal->j_commit_sequence,
+		   journal->j_devname, commit_transaction->t_tid,
 		   journal->j_tail_sequence);
 	jbd_debug(1, "JBD: commit %d complete, head %d\n",
 		  journal->j_commit_sequence, journal->j_tail_sequence);
+	if (to_free)
+		kfree(commit_transaction);
 
 	wake_up(&journal->j_wait_done_commit);
 }
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 973db89..b890ed7 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1146,8 +1146,8 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
 int jbd2_log_do_checkpoint(journal_t *journal);
 
 void __jbd2_log_wait_for_space(journal_t *journal);
-extern void	__jbd2_journal_drop_transaction(journal_t *, transaction_t *);
-extern int	jbd2_cleanup_journal_tail(journal_t *);
+extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
+extern int jbd2_cleanup_journal_tail(journal_t *);
 
 /* Debugging code only: */
 
-- 
1.6.0.3.514.g2f91b

[RFC PATCH -v2 7/9] ext4: don't use the block freed but not yet committed during buddy initialization

[Aneesh Kumar K.V]

When we generate buddy cache(especially during resize) we need to make
sure we don't use the blocks freed but not yet comitted. This make
sure we have the right value of free blocks count in the group
info and also in the bitmap. This also ensures the ordered mode
consistency

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/mballoc.c |   95 ++++++++++++++++++++++++++++++++++++++++-------------
 1 files changed, 72 insertions(+), 23 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 34a365e..f6d9e30 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -335,6 +335,9 @@
 static struct kmem_cache *ext4_free_ext_cachep;
 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
 					ext4_group_t group);
+static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
+					ext4_group_t group,
+					struct ext4_free_data *entry);
 static int ext4_mb_init_per_dev_proc(struct super_block *sb);
 static int ext4_mb_destroy_per_dev_proc(struct super_block *sb);
 static void release_blocks_on_commit(journal_t *journal, transaction_t *txn);
@@ -858,7 +861,9 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
 			/*
 			 * incore got set to the group block bitmap below
 			 */
+			ext4_lock_group(sb, group);
 			ext4_mb_generate_buddy(sb, data, incore, group);
+			ext4_unlock_group(sb, group);
 			incore = NULL;
 		} else {
 			/* this is block of bitmap */
@@ -872,6 +877,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
 
 			/* mark all preallocated blks used in in-core bitmap */
 			ext4_mb_generate_from_pa(sb, data, group);
+			ext4_mb_generate_from_freelist(sb, data, group, NULL);
 			ext4_unlock_group(sb, group);
 
 			/* set incore so that the buddy information can be
@@ -3432,6 +3438,43 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 }
 
 /*
+ * the function goes through all block freed in the group
+ * but not yet committed and marks them used in in-core bitmap.
+ * buddy must be generated from this bitmap
+ * Need to be called with ext4 group lock (ext4_lock_group)
+ */
+static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
+					ext4_group_t group,
+					struct ext4_free_data *entry)
+{
+	struct rb_node *n;
+	struct ext4_group_info *grp;
+	struct ext4_free_data *new_entry;
+	if (entry == NULL) {
+		grp = ext4_get_group_info(sb, group);
+		n = grp->bb_free_root.rb_node;
+		entry = rb_entry(n, struct ext4_free_data, node);
+
+	} else
+		n = &entry->node;
+
+	if (n == NULL)
+		return;
+	if (n->rb_left) {
+		new_entry = rb_entry(n->rb_left, struct ext4_free_data, node);
+		ext4_mb_generate_from_freelist(sb, bitmap, group, new_entry);
+	}
+	if (n->rb_right) {
+		new_entry = rb_entry(n->rb_right, struct ext4_free_data, node);
+		ext4_mb_generate_from_freelist(sb, bitmap, group, new_entry);
+	}
+	mb_set_bits(sb_bgl_lock(EXT4_SB(sb), group),
+					bitmap, entry->start_blk,
+					entry->count);
+	return;
+}
+
+/*
  * the function goes through all preallocation in this group and marks them
  * used in in-core bitmap. buddy must be generated from this bitmap
  * Need to be called with ext4 group lock (ext4_lock_group)
@@ -4532,27 +4575,22 @@ static int can_merge(struct ext4_free_data *entry1,
 
 static noinline_for_stack int
 ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
-			  ext4_group_t group, ext4_grpblk_t block, int count)
+			struct ext4_free_data *new_entry)
 {
+	ext4_grpblk_t block;
+	struct ext4_free_data *entry;
 	struct ext4_group_info *db = e4b->bd_info;
 	struct super_block *sb = e4b->bd_sb;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	struct ext4_free_data *entry, *new_entry;
 	struct rb_node **n = &db->bb_free_root.rb_node, *node;
 	struct rb_node *parent = NULL, *new_node;
 
-
 	BUG_ON(e4b->bd_bitmap_page == NULL);
 	BUG_ON(e4b->bd_buddy_page == NULL);
 
-	new_entry  = kmem_cache_alloc(ext4_free_ext_cachep, GFP_NOFS);
-	new_entry->start_blk = block;
-	new_entry->group  = group;
-	new_entry->count = count;
-	new_entry->t_tid = handle->h_transaction->t_tid;
 	new_node = &new_entry->node;
+	block = new_entry->start_blk;
 
-	ext4_lock_group(sb, group);
 	if (!*n) {
 		/* first free block exent. We need to
 		   protect buddy cache from being freed,
@@ -4570,7 +4608,6 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
 		else if (block >= (entry->start_blk + entry->count))
 			n = &(*n)->rb_right;
 		else {
-			ext4_unlock_group(sb, group);
 			ext4_error(sb, __func__,
 			    "Double free of blocks %d (%d %d)\n",
 			    block, entry->start_blk, entry->count);
@@ -4612,7 +4649,6 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
 	spin_lock(&sbi->s_md_lock);
 	list_add(&new_entry->list, &handle->h_transaction->t_private_list);
 	spin_unlock(&sbi->s_md_lock);
-	ext4_unlock_group(sb, group);
 	return 0;
 }
 
@@ -4717,15 +4753,6 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
 			BUG_ON(!mb_test_bit(bit + i, bitmap_bh->b_data));
 	}
 #endif
-	mb_clear_bits(sb_bgl_lock(sbi, block_group), bitmap_bh->b_data,
-			bit, count);
-
-	/* We dirtied the bitmap block */
-	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
-	err = ext4_journal_dirty_metadata(handle, bitmap_bh);
-	if (err)
-		goto error_return;
-
 	if (ac) {
 		ac->ac_b_ex.fe_group = block_group;
 		ac->ac_b_ex.fe_start = bit;
@@ -4739,11 +4766,29 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
 		goto error_return;
 	}
 	if (metadata) {
-		/* blocks being freed are metadata. these blocks shouldn't
-		 * be used until this transaction is committed */
-		ext4_mb_free_metadata(handle, &e4b, block_group, bit, count);
+		struct ext4_free_data *new_entry;
+		/*
+		 * blocks being freed are metadata. these blocks shouldn't
+		 * be used until this transaction is committed
+		 */
+		new_entry  = kmem_cache_alloc(ext4_free_ext_cachep, GFP_NOFS);
+		new_entry->start_blk = bit;
+		new_entry->group  = block_group;
+		new_entry->count = count;
+		new_entry->t_tid = handle->h_transaction->t_tid;
+		ext4_lock_group(sb, block_group);
+		mb_clear_bits(sb_bgl_lock(sbi, block_group), bitmap_bh->b_data,
+				bit, count);
+		ext4_mb_free_metadata(handle, &e4b, new_entry);
+		ext4_unlock_group(sb, block_group);
 	} else {
 		ext4_lock_group(sb, block_group);
+		/* need to update group_info->bb_free and bitmap
+		 * with group lock held. generate_buddy look at
+		 * them with group lock_held
+		 */
+		mb_clear_bits(sb_bgl_lock(sbi, block_group), bitmap_bh->b_data,
+				bit, count);
 		mb_free_blocks(inode, &e4b, bit, count);
 		ext4_mb_return_to_preallocation(inode, &e4b, block, count);
 		ext4_unlock_group(sb, block_group);
@@ -4766,6 +4811,10 @@ void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
 
 	*freed += count;
 
+	/* We dirtied the bitmap block */
+	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
+	err = ext4_journal_dirty_metadata(handle, bitmap_bh);
+
 	/* And the group descriptor block */
 	BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 	ret = ext4_journal_dirty_metadata(handle, gd_bh);
-- 
1.6.0.3.514.g2f91b

[RFC PATCH -v2 8/9] ext4: Fix double free of blocks

[Aneesh Kumar K.V]

blocks freed but not yet committed will be marked free
in disk bitmap. We need to consider them as used when
releasing inode prealloc space. Otherwise we would
double free them via mb_free_blocks

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/mballoc.c |   72 +++++++++++++++++++++++++++++++++-------------------
 1 files changed, 46 insertions(+), 26 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index f6d9e30..c169256 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3454,7 +3454,6 @@ static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
 		grp = ext4_get_group_info(sb, group);
 		n = grp->bb_free_root.rb_node;
 		entry = rb_entry(n, struct ext4_free_data, node);
-
 	} else
 		n = &entry->node;
 
@@ -3741,19 +3740,19 @@ static int ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
  * TODO: optimize the case when there are no in-core structures yet
  */
 static noinline_for_stack int
-ext4_mb_release_inode_pa(struct ext4_buddy *e4b, struct buffer_head *bitmap_bh,
+ext4_mb_release_inode_pa(struct ext4_buddy *e4b, void *bitmap,
 			struct ext4_prealloc_space *pa,
 			struct ext4_allocation_context *ac)
 {
-	struct super_block *sb = e4b->bd_sb;
-	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	int err = 0;
+	int free = 0;
+	sector_t start;
 	unsigned long end;
 	unsigned long next;
 	ext4_group_t group;
 	ext4_grpblk_t bit;
-	sector_t start;
-	int err = 0;
-	int free = 0;
+	struct super_block *sb = e4b->bd_sb;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
 
 	BUG_ON(pa->pa_deleted == 0);
 	ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit);
@@ -3765,12 +3764,11 @@ ext4_mb_release_inode_pa(struct ext4_buddy *e4b, struct buffer_head *bitmap_bh,
 		ac->ac_inode = pa->pa_inode;
 		ac->ac_op = EXT4_MB_HISTORY_DISCARD;
 	}
-
 	while (bit < end) {
-		bit = mb_find_next_zero_bit(bitmap_bh->b_data, end, bit);
+		bit = mb_find_next_zero_bit(bitmap, end, bit);
 		if (bit >= end)
 			break;
-		next = mb_find_next_bit(bitmap_bh->b_data, end, bit);
+		next = mb_find_next_bit(bitmap, end, bit);
 		start = group * EXT4_BLOCKS_PER_GROUP(sb) + bit +
 				le32_to_cpu(sbi->s_es->s_first_data_block);
 		mb_debug("    free preallocated %u/%u in group %u\n",
@@ -3789,18 +3787,12 @@ ext4_mb_release_inode_pa(struct ext4_buddy *e4b, struct buffer_head *bitmap_bh,
 		mb_free_blocks(pa->pa_inode, e4b, bit, next - bit);
 		bit = next + 1;
 	}
-	if (free != pa->pa_free) {
-		printk(KERN_CRIT "pa %p: logic %lu, phys. %lu, len %lu\n",
-			pa, (unsigned long) pa->pa_lstart,
-			(unsigned long) pa->pa_pstart,
-			(unsigned long) pa->pa_len);
-		ext4_error(sb, __func__, "free %u, pa_free %u\n",
-						free, pa->pa_free);
-		/*
-		 * pa is already deleted so we use the value obtained
-		 * from the bitmap and continue.
-		 */
-	}
+	/*
+	 * The blocks allocated and later freed from this pa
+	 * can result in pa_free being different from the
+	 * bitmap free block count. This is because we don't
+	 * update pa_len on releasing blocks.
+	 */
 	atomic_add(free, &sbi->s_mb_discarded);
 
 	return err;
@@ -3856,6 +3848,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 	struct ext4_allocation_context *ac;
 	struct list_head list;
 	struct ext4_buddy e4b;
+	void *bitmap;
 	int err;
 	int busy = 0;
 	int free = 0;
@@ -3871,12 +3864,21 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 				"bitmap for %lu\n", group);
 		return 0;
 	}
-
+	/* blocks freed but not yet committed will
+	 * be marked free in disk bitmap. We need to
+	 * consider them as used when releasing inode
+	 * pa. Otherwise we would double free them
+	 * via mb_free_blocks
+	 */
+	bitmap = kmalloc(sb->s_blocksize, GFP_NOFS);
+	if (!bitmap)
+		return 0;
 	err = ext4_mb_load_buddy(sb, group, &e4b);
 	if (err) {
 		__release(e4b->alloc_semp);
 		ext4_error(sb, __func__, "Error in loading buddy "
 				"information for %lu\n", group);
+		kfree(bitmap);
 		put_bh(bitmap_bh);
 		return 0;
 	}
@@ -3931,6 +3933,8 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 		goto out;
 	}
 
+	memcpy(bitmap, bitmap_bh->b_data, sb->s_blocksize);
+	ext4_mb_generate_from_freelist(sb, bitmap, group, NULL);
 	/* now free all selected PAs */
 	list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
 
@@ -3942,7 +3946,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 		if (pa->pa_linear)
 			ext4_mb_release_group_pa(&e4b, pa, ac);
 		else
-			ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa, ac);
+			ext4_mb_release_inode_pa(&e4b, bitmap, pa, ac);
 
 		list_del(&pa->u.pa_tmp_list);
 		call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
@@ -3953,6 +3957,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 	if (ac)
 		kmem_cache_free(ext4_ac_cachep, ac);
 	ext4_mb_release_desc(&e4b);
+	kfree(bitmap);
 	put_bh(bitmap_bh);
 	return free;
 }
@@ -3977,6 +3982,7 @@ void ext4_discard_preallocations(struct inode *inode)
 	struct list_head list;
 	struct ext4_buddy e4b;
 	int err;
+	void *bitmap;
 
 	if (!S_ISREG(inode->i_mode)) {
 		/*BUG_ON(!list_empty(&ei->i_prealloc_list));*/
@@ -4055,14 +4061,28 @@ void ext4_discard_preallocations(struct inode *inode)
 			ext4_mb_release_desc(&e4b);
 			continue;
 		}
-
+		/* blocks freed but not yet committed will
+		 * be marked free in disk bitmap. We need to
+		 * consider them as used when releasing inode
+		 * pa. Otherwise we would double free them
+		 * via mb_free_blocks
+		 */
+		bitmap = kmalloc(sb->s_blocksize, GFP_NOFS);
+		if (!bitmap) {
+			ext4_mb_release_desc(&e4b);
+			put_bh(bitmap_bh);
+			continue;
+		}
+		memcpy(bitmap, bitmap_bh->b_data, sb->s_blocksize);
 		ext4_lock_group(sb, group);
+		ext4_mb_generate_from_freelist(sb, bitmap, group, NULL);
 		list_del(&pa->pa_group_list);
-		ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa, ac);
+		ext4_mb_release_inode_pa(&e4b, bitmap, pa, ac);
 		ext4_unlock_group(sb, group);
 
 		ext4_mb_release_desc(&e4b);
 		put_bh(bitmap_bh);
+		kfree(bitmap);
 
 		list_del(&pa->u.pa_tmp_list);
 		call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
-- 
1.6.0.3.514.g2f91b

[RFC PATCH -v2 9/9] ext4: Fix lockdep recursive locking warning

[Aneesh Kumar K.V]

Indicate that the group locks can be taken in loop.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/mballoc.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c169256..5a5f9e1 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2418,6 +2418,7 @@ ext4_mb_store_history(struct ext4_allocation_context *ac)
 #define ext4_mb_history_init(sb)
 #endif
 
+static struct lock_class_key alloc_sem_key[NR_BG_LOCKS];
 
 /* Create and initialize ext4_group_info data for the given group. */
 int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
@@ -2478,7 +2479,9 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
 	}
 
 	INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list);
-	init_rwsem(&meta_group_info[i]->alloc_sem);
+	__init_rwsem(&meta_group_info[i]->alloc_sem,
+			"&meta_group_info[i]->alloc_sem",
+			&alloc_sem_key[i]);
 	meta_group_info[i]->bb_free_root.rb_node = NULL;;
 
 #ifdef DOUBLE_CHECK
-- 
1.6.0.3.514.g2f91b

Re: [RFC PATCH -v2 9/9] ext4: Fix lockdep recursive locking warning

[Theodore Tso]

Ok, I've added all of your patches into the ext4 patch queues.  For
the most part I haven't made any changes to the patches, other than
adding my signed-off-by.

						- Ted

Re: [RFC PATCH -v2 8/9] ext4: Fix double free of blocks

[Theodore Tso]

On Mon, Nov 03, 2008 at 11:06:08PM +0530, Aneesh Kumar K.V wrote:
> blocks freed but not yet committed will be marked free
> in disk bitmap. We need to consider them as used when
> releasing inode prealloc space. Otherwise we would
> double free them via mb_free_blocks

Stupid question...   

Blocks that are added to an inode's preallocation list were initially
free, right?  And once they are in the inode's preallocation they are
marked in use by mballoc, so they can't be allocated for another
inode.  If a block in the preallocation list is used, it's removed
from the preallocation line.  So even if that inode is subsequented
unlinked or truncated, I'm curious how the double free situation
happens in the first place.

What am I missing?

					- Ted

Re: [RFC PATCH -v2 8/9] ext4: Fix double free of blocks

[Aneesh Kumar K.V]

On Tue, Nov 04, 2008 at 11:46:04AM -0500, Theodore Tso wrote:
> On Mon, Nov 03, 2008 at 11:06:08PM +0530, Aneesh Kumar K.V wrote:
> > blocks freed but not yet committed will be marked free
> > in disk bitmap. We need to consider them as used when
> > releasing inode prealloc space. Otherwise we would
> > double free them via mb_free_blocks
> 
> Stupid question...   
> 
> Blocks that are added to an inode's preallocation list were initially
> free, right?  And once they are in the inode's preallocation they are
> marked in use by mballoc, so they can't be allocated for another
> inode.  If a block in the preallocation list is used, it's removed
> from the preallocation line.  So even if that inode is subsequented
> unlinked or truncated, I'm curious how the double free situation
> happens in the first place.
> 
> What am I missing?
> 

We we discard  inode preallocation we look at the block bitmap
and mark the blocks found free in the bitmap using mb_free_blocks.
Now if we  allocate some blocks and later free some of them we would
have called ext4_mb_free blocks on them which mean we would have
marked the blocks free on bitmap. Now on file close we release
inode pa. We look at the block bitmap and if the block is free
in bitmap we call mb_free_blocks. Also on committing the transaction we
call mb_free_blocks on them. To avoid the above we need to make sure
when we discard_inode_pa we look at a bitmap that have block freed
and not yet committed as used.

-aneesh

Re: [RFC PATCH -v2 7/9] ext4: don't use the block freed but not yet committed during buddy initialization

[Theodore Tso]

On Mon, Nov 03, 2008 at 11:06:07PM +0530, Aneesh Kumar K.V wrote:
> +static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
> +					ext4_group_t group,
> +					struct ext4_free_data *entry)
> +{
	...
> +	if (n->rb_left) {
> +		new_entry = rb_entry(n->rb_left, struct ext4_free_data, node);
> +		ext4_mb_generate_from_freelist(sb, bitmap, group, new_entry);
> +	}
> +	if (n->rb_right) {
> +		new_entry = rb_entry(n->rb_right, struct ext4_free_data, node);
> +		ext4_mb_generate_from_freelist(sb, bitmap, group, new_entry);
> +	}

ext4_mb_generate_from_freelist() is recursively calling itself, which
could easily blow the stack if there are a large number of items on
the free list (remember, this can include data blocks if
!ext4_should_writeback_data()).

You should probably use rb_first and rb_next in a loop rather than a
recursive descent.  I also remain concerned that
ext4_mb_generate_from_freelist() is could burn a large amount of CPU
in some cases, and as I said on the conference call, if there is a way
to avoid it, that would be a Good Thing.

						- Ted

Re: [RFC PATCH -v2 7/9] ext4: don't use the block freed but not yet committed during buddy initialization

[Aneesh Kumar K.V]

On Tue, Nov 04, 2008 at 12:15:15PM -0500, Theodore Tso wrote:
> On Mon, Nov 03, 2008 at 11:06:07PM +0530, Aneesh Kumar K.V wrote:
> > +static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
> > +					ext4_group_t group,
> > +					struct ext4_free_data *entry)
> > +{
> 	...
> > +	if (n->rb_left) {
> > +		new_entry = rb_entry(n->rb_left, struct ext4_free_data, node);
> > +		ext4_mb_generate_from_freelist(sb, bitmap, group, new_entry);
> > +	}
> > +	if (n->rb_right) {
> > +		new_entry = rb_entry(n->rb_right, struct ext4_free_data, node);
> > +		ext4_mb_generate_from_freelist(sb, bitmap, group, new_entry);
> > +	}
> 
> ext4_mb_generate_from_freelist() is recursively calling itself, which
> could easily blow the stack if there are a large number of items on
> the free list (remember, this can include data blocks if
> !ext4_should_writeback_data()).
> 
> You should probably use rb_first and rb_next in a loop rather than a
> recursive descent. 

Will do this.

>I also remain concerned that
> ext4_mb_generate_from_freelist() is could burn a large amount of CPU
> in some cases, and as I said on the conference call, if there is a way
> to avoid it, that would be a Good Thing.

We need ext4_mb_generate_from_freelist for multiple case

a) While generating the buddy information we need to make sure we don't
use the blocks released but not yet committed to disk. We may force
buddy rebuild because we added a new group via resize. We need to do
a buddy rebuild irrespective of whether we use ext4_mb_free_blocks or
EXT4_MB_GRP_NEED_INIT flag

b) We we release inode preallocation we look at the block bitmap
and mark the blocks found free in the bitmap using mb_free_blocks.
Now if we  allocate some blocks and later free some of them we may 
have called ext4_mb_free blocks on them which mean we would have
marked the blocks free on bitmap. Now on file close we release
inode pa. We look at the block bitmap and if the block is free
in bitmap we call mb_free_blocks. Also on committing the transaction we
call mb_free_blocks on them. To avoid the above we need to make sure
when we discard_inode_pa we look at a bitmap that have block freed
and not yet committed as used.

-aneesh

Re: [RFC PATCH -v2 6/9] ext4: Call journal commit callback without holding j_list_lock

[Theodore Tso]

I suggest adding the following description and to change the prefix to
be jbd2, not ext4, since the change applies 100% to jbd2 code (and so
it could potentially apply to ocfs2 if they decide to use this
callback, for example).

jbd2: Call journal commit callback without holding j_list_lock

Avoid freeing the transaction in __jbd2_journal_drop_transaction() so
the journal commit callback can run without holding j_list_lock, to
avoid lock contention on this spinlock.

						- Ted

Re: [RFC PATCH -v2 6/9] ext4: Call journal commit callback without holding j_list_lock

[Theodore Tso]

I've had to break this patch into two parts, since one hunk only
applies after defrag-06-add-ioc-free-blocks-info-ioctl.

						- Ted

Re: [RFC PATCH -v2 5/9] ext4: sparse annotate the group info semaphore

[Theodore Tso]

I changed the description of this patch to be more grammatically
correct:

ext4: Add sparse annotations for the group info semaphore

Hmm...  Why not merge this with patch #3, "ext4: Use
EXT4_GROUP_INFO_NEED_INIT_BIT during resize" where alloc_semp is newly
defined?

      	  	 	     	     	   	- Ted

Re: [RFC PATCH -v2 5/9] ext4: sparse annotate the group info semaphore

[Aneesh Kumar K.V]

On Tue, Nov 04, 2008 at 12:43:57PM -0500, Theodore Tso wrote:
> I changed the description of this patch to be more grammatically
> correct:
> 
> ext4: Add sparse annotations for the group info semaphore
> 
> Hmm...  Why not merge this with patch #3, "ext4: Use
> EXT4_GROUP_INFO_NEED_INIT_BIT during resize" where alloc_semp is newly
> defined?
> 

Mostly because I found the error path annotation ugly. It is easier to
fold the patch later than split. I wanted to make sure it is the right
way to annotate.

-aneesh

Re: [RFC PATCH -v2 3/9] ext4: Use EXT4_GROUP_INFO_NEED_INIT_BIT during resize

[Theodore Tso]

On Mon, Nov 03, 2008 at 11:06:03PM +0530, Aneesh Kumar K.V wrote:
> The new groups added during resize are flagged as
> need_init group. Make sure we properly initialize these
> groups. When we have block size < page size and we are adding
> new groups the page may still be marked uptodate even though
> we haven't initialized the group.

Aneesh, can you explain to me again why we can't just call
ext4_mb_free_blocks().  I thought I heard you say that the buddy
bitmaps weren't appropriately initialized for the end of the bitmap
--- but I just went through mballoc.c and I couldn't see the problem.
What am I missing?

						- Ted

Re: [RFC PATCH -v2 3/9] ext4: Use EXT4_GROUP_INFO_NEED_INIT_BIT during resize

[Aneesh Kumar K.V]

On Tue, Nov 04, 2008 at 01:00:44PM -0500, Theodore Tso wrote:
> On Mon, Nov 03, 2008 at 11:06:03PM +0530, Aneesh Kumar K.V wrote:
> > The new groups added during resize are flagged as
> > need_init group. Make sure we properly initialize these
> > groups. When we have block size < page size and we are adding
> > new groups the page may still be marked uptodate even though
> > we haven't initialized the group.
> 
> Aneesh, can you explain to me again why we can't just call
> ext4_mb_free_blocks().  I thought I heard you say that the buddy
> bitmaps weren't appropriately initialized for the end of the bitmap
> --- but I just went through mballoc.c and I couldn't see the problem.
> What am I missing?
> 

We should be able to use ext4_mb_free_blocks() during resize provided
we fix mb_load_buddy to handle the new block group added. Frederic's 
patch actually did that. The problem is with blocksize less than page
size, we need to be more careful when looking at the uptodate flag of the
page because the new block group added can have its bitmap as a part of
already used/uptodate page. So in short we would need some flags to indicate
that that even though the page is marked as uptodate we would like to
force init the buddy cache(ie, call ext4_mb_init_cache). Which in turn would
require us to make sure no parallel load_buddy is happening.(currently
ensured by alloc_sem in the patch series). This is because we are doing
a reinit of the page. I actually tried to do it that way first. But
found the code to more confusing with all the locking.

-aneesh

Re: [RFC PATCH -v2 1/9] ext4: sparse fixes

[Theodore Tso]

In the next version of the patch, can you also remove the declaration
of ext4_fiemap() in fs/ext4/file.c?

Thanks!!

						- Ted