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ext4: Cleanup the block reservation code path
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The truncate patch should not use the i_allocated_meta_blocks
value. So add seperate functions to be used in the truncate
and alloc path. We also need to release the meta-data block
that we reserved for the blocks that we are truncating.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Aneesh Kumar K.V authored and Theodore Ts'o committed Jul 17, 2008
1 parent 34071da commit 12219ae
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Showing 2 changed files with 67 additions and 42 deletions.
1 change: 0 additions & 1 deletion fs/ext4/ext4.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1044,7 +1044,6 @@ extern void ext4_mb_update_group_info(struct ext4_group_info *grp,


/* inode.c */
void ext4_da_release_space(struct inode *inode, int used, int to_free);
int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
struct buffer_head *bh, ext4_fsblk_t blocknr);
struct buffer_head *ext4_getblk(handle_t *, struct inode *,
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108 changes: 67 additions & 41 deletions fs/ext4/inode.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -980,6 +980,67 @@ int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
return err;
}

/*
* Calculate the number of metadata blocks need to reserve
* to allocate @blocks for non extent file based file
*/
static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
{
int icap = EXT4_ADDR_PER_BLOCK(inode->i_sb);
int ind_blks, dind_blks, tind_blks;

/* number of new indirect blocks needed */
ind_blks = (blocks + icap - 1) / icap;

dind_blks = (ind_blks + icap - 1) / icap;

tind_blks = 1;

return ind_blks + dind_blks + tind_blks;
}

/*
* Calculate the number of metadata blocks need to reserve
* to allocate given number of blocks
*/
static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
{
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
return ext4_ext_calc_metadata_amount(inode, blocks);

return ext4_indirect_calc_metadata_amount(inode, blocks);
}

static void ext4_da_update_reserve_space(struct inode *inode, int used)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
int total, mdb, mdb_free;

spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
/* recalculate the number of metablocks still need to be reserved */
total = EXT4_I(inode)->i_reserved_data_blocks - used;
mdb = ext4_calc_metadata_amount(inode, total);

/* figure out how many metablocks to release */
BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;

/* Account for allocated meta_blocks */
mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;

/* update fs free blocks counter for truncate case */
percpu_counter_add(&sbi->s_freeblocks_counter, mdb_free);

/* update per-inode reservations */
BUG_ON(used > EXT4_I(inode)->i_reserved_data_blocks);
EXT4_I(inode)->i_reserved_data_blocks -= used;

BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
EXT4_I(inode)->i_reserved_meta_blocks = mdb;
EXT4_I(inode)->i_allocated_meta_blocks = 0;
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
}

/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
/*
Expand Down Expand Up @@ -1097,7 +1158,7 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
* which were deferred till now
*/
if ((retval > 0) && buffer_delay(bh))
ext4_da_release_space(inode, retval, 0);
ext4_da_update_reserve_space(inode, retval);
}

up_write((&EXT4_I(inode)->i_data_sem));
Expand Down Expand Up @@ -1465,36 +1526,6 @@ static int ext4_journalled_write_end(struct file *file,

return ret ? ret : copied;
}
/*
* Calculate the number of metadata blocks need to reserve
* to allocate @blocks for non extent file based file
*/
static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
{
int icap = EXT4_ADDR_PER_BLOCK(inode->i_sb);
int ind_blks, dind_blks, tind_blks;

/* number of new indirect blocks needed */
ind_blks = (blocks + icap - 1) / icap;

dind_blks = (ind_blks + icap - 1) / icap;

tind_blks = 1;

return ind_blks + dind_blks + tind_blks;
}

/*
* Calculate the number of metadata blocks need to reserve
* to allocate given number of blocks
*/
static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
{
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
return ext4_ext_calc_metadata_amount(inode, blocks);

return ext4_indirect_calc_metadata_amount(inode, blocks);
}

static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
{
Expand All @@ -1518,7 +1549,6 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
return -ENOSPC;
}

/* reduce fs free blocks counter */
percpu_counter_sub(&sbi->s_freeblocks_counter, total);

Expand All @@ -1529,35 +1559,31 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
return 0; /* success */
}

void ext4_da_release_space(struct inode *inode, int used, int to_free)
static void ext4_da_release_space(struct inode *inode, int to_free)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
int total, mdb, mdb_free, release;

spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
/* recalculate the number of metablocks still need to be reserved */
total = EXT4_I(inode)->i_reserved_data_blocks - used - to_free;
total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
mdb = ext4_calc_metadata_amount(inode, total);

/* figure out how many metablocks to release */
BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;

/* Account for allocated meta_blocks */
mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;

release = to_free + mdb_free;

/* update fs free blocks counter for truncate case */
percpu_counter_add(&sbi->s_freeblocks_counter, release);

/* update per-inode reservations */
BUG_ON(used + to_free > EXT4_I(inode)->i_reserved_data_blocks);
EXT4_I(inode)->i_reserved_data_blocks -= (used + to_free);
BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks);
EXT4_I(inode)->i_reserved_data_blocks -= to_free;

BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
EXT4_I(inode)->i_reserved_meta_blocks = mdb;
EXT4_I(inode)->i_allocated_meta_blocks = 0;
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
}

Expand All @@ -1579,7 +1605,7 @@ static void ext4_da_page_release_reservation(struct page *page,
}
curr_off = next_off;
} while ((bh = bh->b_this_page) != head);
ext4_da_release_space(page->mapping->host, 0, to_release);
ext4_da_release_space(page->mapping->host, to_release);
}

/*
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