From c9b832385f007ceac33b7515f24f2f2dcfd9c2ce Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sun, 30 May 2010 22:49:23 -0400 Subject: [PATCH] ext4: Calculate metadata requirements more accurately commit 9d0be50230b333005635967f7ecd4897dbfd181b upstream (as of v2.6.33-rc3) In the past, ext4_calc_metadata_amount(), and its sub-functions ext4_ext_calc_metadata_amount() and ext4_indirect_calc_metadata_amount() badly over-estimated the number of metadata blocks that might be required for delayed allocation blocks. This didn't matter as much when functions which managed the reserved metadata blocks were more aggressive about dropping reserved metadata blocks as delayed allocation blocks were written, but unfortunately they were too aggressive. This was fixed in commit 0637c6f, but as a result the over-estimation by ext4_calc_metadata_amount() would lead to reserving 2-3 times the number of pending delayed allocation blocks as potentially required metadata blocks. So if there are 1 megabytes of blocks which have been not yet been allocation, up to 3 megabytes of space would get reserved out of the user's quota and from the file system free space pool until all of the inode's data blocks have been allocated. This commit addresses this problem by much more accurately estimating the number of metadata blocks that will be required. It will still somewhat over-estimate the number of blocks needed, since it must make a worst case estimate not knowing which physical blocks will be needed, but it is much more accurate than before. Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman --- fs/ext4/ext4.h | 2 ++ fs/ext4/ext4_extents.h | 3 +- fs/ext4/extents.c | 49 +++++++++++++++++++++------------ fs/ext4/inode.c | 62 ++++++++++++++++++++++++------------------ fs/ext4/super.c | 1 + 5 files changed, 73 insertions(+), 44 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 4a825c129c16..23bfbbcd8933 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -693,6 +693,8 @@ struct ext4_inode_info { unsigned int i_reserved_meta_blocks; unsigned int i_allocated_meta_blocks; unsigned short i_delalloc_reserved_flag; + sector_t i_da_metadata_calc_last_lblock; + int i_da_metadata_calc_len; /* on-disk additional length */ __u16 i_extra_isize; diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h index 2ca686454e87..bdb6ce7e2eb4 100644 --- a/fs/ext4/ext4_extents.h +++ b/fs/ext4/ext4_extents.h @@ -225,7 +225,8 @@ static inline void ext4_ext_mark_initialized(struct ext4_extent *ext) ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext)); } -extern int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks); +extern int ext4_ext_calc_metadata_amount(struct inode *inode, + sector_t lblocks); extern ext4_fsblk_t ext_pblock(struct ext4_extent *ex); extern ext4_fsblk_t idx_pblock(struct ext4_extent_idx *); extern void ext4_ext_store_pblock(struct ext4_extent *, ext4_fsblk_t); diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index b14fb6d695c7..5f03f9f99338 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -296,29 +296,44 @@ static inline int ext4_ext_space_root_idx(struct inode *inode, int check) * to allocate @blocks * Worse case is one block per extent */ -int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks) +int ext4_ext_calc_metadata_amount(struct inode *inode, sector_t lblock) { - int lcap, icap, rcap, leafs, idxs, num; - int newextents = blocks; - - rcap = ext4_ext_space_root_idx(inode, 0); - lcap = ext4_ext_space_block(inode, 0); - icap = ext4_ext_space_block_idx(inode, 0); + struct ext4_inode_info *ei = EXT4_I(inode); + int idxs, num = 0; - /* number of new leaf blocks needed */ - num = leafs = (newextents + lcap - 1) / lcap; + idxs = ((inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header)) + / sizeof(struct ext4_extent_idx)); /* - * Worse case, we need separate index block(s) - * to link all new leaf blocks + * If the new delayed allocation block is contiguous with the + * previous da block, it can share index blocks with the + * previous block, so we only need to allocate a new index + * block every idxs leaf blocks. At ldxs**2 blocks, we need + * an additional index block, and at ldxs**3 blocks, yet + * another index blocks. */ - idxs = (leafs + icap - 1) / icap; - do { - num += idxs; - idxs = (idxs + icap - 1) / icap; - } while (idxs > rcap); + if (ei->i_da_metadata_calc_len && + ei->i_da_metadata_calc_last_lblock+1 == lblock) { + if ((ei->i_da_metadata_calc_len % idxs) == 0) + num++; + if ((ei->i_da_metadata_calc_len % (idxs*idxs)) == 0) + num++; + if ((ei->i_da_metadata_calc_len % (idxs*idxs*idxs)) == 0) { + num++; + ei->i_da_metadata_calc_len = 0; + } else + ei->i_da_metadata_calc_len++; + ei->i_da_metadata_calc_last_lblock++; + return num; + } - return num; + /* + * In the worst case we need a new set of index blocks at + * every level of the inode's extent tree. + */ + ei->i_da_metadata_calc_len = 1; + ei->i_da_metadata_calc_last_lblock = lblock; + return ext_depth(inode) + 1; } static int diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c3e1d0fda4d0..142be0e4e75e 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1051,38 +1051,44 @@ qsize_t *ext4_get_reserved_space(struct inode *inode) return &EXT4_I(inode)->i_reserved_quota; } #endif + /* * Calculate the number of metadata blocks need to reserve - * to allocate @blocks for non extent file based file + * to allocate a new block at @lblocks for non extent file based file */ -static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks) +static int ext4_indirect_calc_metadata_amount(struct inode *inode, + sector_t lblock) { - 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; + struct ext4_inode_info *ei = EXT4_I(inode); + int dind_mask = EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1; + int blk_bits; - dind_blks = (ind_blks + icap - 1) / icap; + if (lblock < EXT4_NDIR_BLOCKS) + return 0; - tind_blks = 1; + lblock -= EXT4_NDIR_BLOCKS; - return ind_blks + dind_blks + tind_blks; + if (ei->i_da_metadata_calc_len && + (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) { + ei->i_da_metadata_calc_len++; + return 0; + } + ei->i_da_metadata_calc_last_lblock = lblock & dind_mask; + ei->i_da_metadata_calc_len = 1; + blk_bits = roundup_pow_of_two(lblock + 1); + return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1; } /* * Calculate the number of metadata blocks need to reserve - * to allocate given number of blocks + * to allocate a block located at @lblock */ -static int ext4_calc_metadata_amount(struct inode *inode, int blocks) +static int ext4_calc_metadata_amount(struct inode *inode, sector_t lblock) { - if (!blocks) - return 0; - if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) - return ext4_ext_calc_metadata_amount(inode, blocks); + return ext4_ext_calc_metadata_amount(inode, lblock); - return ext4_indirect_calc_metadata_amount(inode, blocks); + return ext4_indirect_calc_metadata_amount(inode, lblock); } /* @@ -1120,6 +1126,7 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used) */ mdb_free = ei->i_reserved_meta_blocks; ei->i_reserved_meta_blocks = 0; + ei->i_da_metadata_calc_len = 0; percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free); } spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); @@ -1844,12 +1851,15 @@ static int ext4_journalled_write_end(struct file *file, return ret ? ret : copied; } -static int ext4_da_reserve_space(struct inode *inode, int nrblocks) +/* + * Reserve a single block located at lblock + */ +static int ext4_da_reserve_space(struct inode *inode, sector_t lblock) { int retries = 0; struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); struct ext4_inode_info *ei = EXT4_I(inode); - unsigned long md_needed, md_reserved, total = 0; + unsigned long md_needed, md_reserved; /* * recalculate the amount of metadata blocks to reserve @@ -1859,8 +1869,7 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks) repeat: spin_lock(&ei->i_block_reservation_lock); md_reserved = ei->i_reserved_meta_blocks; - md_needed = ext4_calc_metadata_amount(inode, nrblocks); - total = md_needed + nrblocks; + md_needed = ext4_calc_metadata_amount(inode, lblock); spin_unlock(&ei->i_block_reservation_lock); /* @@ -1868,7 +1877,7 @@ repeat: * later. Real quota accounting is done at pages writeout * time. */ - if (vfs_dq_reserve_block(inode, total)) { + if (vfs_dq_reserve_block(inode, md_needed + 1)) { /* * We tend to badly over-estimate the amount of * metadata blocks which are needed, so if we have @@ -1880,8 +1889,8 @@ repeat: return -EDQUOT; } - if (ext4_claim_free_blocks(sbi, total)) { - vfs_dq_release_reservation_block(inode, total); + if (ext4_claim_free_blocks(sbi, md_needed + 1)) { + vfs_dq_release_reservation_block(inode, md_needed + 1); if (ext4_should_retry_alloc(inode->i_sb, &retries)) { retry: if (md_reserved) @@ -1892,7 +1901,7 @@ repeat: return -ENOSPC; } spin_lock(&ei->i_block_reservation_lock); - ei->i_reserved_data_blocks += nrblocks; + ei->i_reserved_data_blocks++; ei->i_reserved_meta_blocks += md_needed; spin_unlock(&ei->i_block_reservation_lock); @@ -1933,6 +1942,7 @@ static void ext4_da_release_space(struct inode *inode, int to_free) */ to_free += ei->i_reserved_meta_blocks; ei->i_reserved_meta_blocks = 0; + ei->i_da_metadata_calc_len = 0; } /* update fs dirty blocks counter */ @@ -2546,7 +2556,7 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock, * XXX: __block_prepare_write() unmaps passed block, * is it OK? */ - ret = ext4_da_reserve_space(inode, 1); + ret = ext4_da_reserve_space(inode, iblock); if (ret) /* not enough space to reserve */ return ret; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 92943f2ca2ab..252f30b6bb61 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -702,6 +702,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb) ei->i_reserved_data_blocks = 0; ei->i_reserved_meta_blocks = 0; ei->i_allocated_meta_blocks = 0; + ei->i_da_metadata_calc_len = 0; ei->i_delalloc_reserved_flag = 0; spin_lock_init(&(ei->i_block_reservation_lock)); #ifdef CONFIG_QUOTA -- 2.39.5