ext4: remove metadata reservation checks

Commit 27dd43854227b ("ext4: introduce reserved space") reserves 2% of
the file system space to make sure metadata allocations will always
succeed.  Given that, tracking the reservation of metadata blocks is
no longer necessary.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

5 files changed, 7 insertions, 141 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index fca382037ddd..581ef40fbe90 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -639,7 +639,6 @@ ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
         if (!(*errp) &&
             ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
-                EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
                 dquot_alloc_block_nofail(inode,
                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 7cc5a0e23688..d35c78c96184 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -591,7 +591,6 @@ enum {
 #define EXT4_FREE_BLOCKS_NO_QUOT_UPDATE 0x0008
 #define EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER   0x0010
 #define EXT4_FREE_BLOCKS_NOFREE_LAST_CLUSTER    0x0020
-#define EXT4_FREE_BLOCKS_RESERVE                0x0040
 
 /*
  * ioctl commands
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 4da228a0e6d0..b30172dd55eb 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1808,8 +1808,7 @@ static void ext4_ext_try_to_merge_up(handle_t *handle,
 
         brelse(path[1].p_bh);
         ext4_free_blocks(handle, inode, NULL, blk, 1,
-                         EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET |
-                         EXT4_FREE_BLOCKS_RESERVE);
+                         EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 }
 
 /*
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8a064734e6eb..027ee8c40470 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -325,18 +325,6 @@ qsize_t *ext4_get_reserved_space(struct inode *inode)
 #endif
 
 /*
- * Calculate the number of metadata blocks need to reserve
- * to allocate a block located at @lblock
- */
-static int ext4_calc_metadata_amount(struct inode *inode, ext4_lblk_t lblock)
-{
-        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
-                return ext4_ext_calc_metadata_amount(inode, lblock);
-
-        return ext4_ind_calc_metadata_amount(inode, lblock);
-}
-
-/*
  * Called with i_data_sem down, which is important since we can call
  * ext4_discard_preallocations() from here.
  */
@@ -357,35 +345,10 @@ void ext4_da_update_reserve_space(struct inode *inode,
                 used = ei->i_reserved_data_blocks;
         }
 
-        if (unlikely(ei->i_allocated_meta_blocks > ei->i_reserved_meta_blocks)) {
-                ext4_warning(inode->i_sb, "ino %lu, allocated %d "
-                        "with only %d reserved metadata blocks "
-                        "(releasing %d blocks with reserved %d data blocks)",
-                        inode->i_ino, ei->i_allocated_meta_blocks,
-                             ei->i_reserved_meta_blocks, used,
-                             ei->i_reserved_data_blocks);
-                WARN_ON(1);
-                ei->i_allocated_meta_blocks = ei->i_reserved_meta_blocks;
-        }
-
         /* Update per-inode reservations */
         ei->i_reserved_data_blocks -= used;
-        ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
-        percpu_counter_sub(&sbi->s_dirtyclusters_counter,
-                           used + ei->i_allocated_meta_blocks);
-        ei->i_allocated_meta_blocks = 0;
+        percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
 
-        if (ei->i_reserved_data_blocks == 0) {
-                /*
-                 * We can release all of the reserved metadata blocks
-                 * only when we have written all of the delayed
-                 * allocation blocks.
-                 */
-                percpu_counter_sub(&sbi->s_dirtyclusters_counter,
-                                   ei->i_reserved_meta_blocks);
-                ei->i_reserved_meta_blocks = 0;
-                ei->i_da_metadata_calc_len = 0;
-        }
         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 
         /* Update quota subsystem for data blocks */
@@ -1222,49 +1185,6 @@ static int ext4_journalled_write_end(struct file *file,
 }
 
 /*
- * Reserve a metadata for a single block located at lblock
- */
-static int ext4_da_reserve_metadata(struct inode *inode, ext4_lblk_t lblock)
-{
-        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-        struct ext4_inode_info *ei = EXT4_I(inode);
-        unsigned int md_needed;
-        ext4_lblk_t save_last_lblock;
-        int save_len;
-
-        /*
-         * recalculate the amount of metadata blocks to reserve
-         * in order to allocate nrblocks
-         * worse case is one extent per block
-         */
-        spin_lock(&ei->i_block_reservation_lock);
-        /*
-         * ext4_calc_metadata_amount() has side effects, which we have
-         * to be prepared undo if we fail to claim space.
-         */
-        save_len = ei->i_da_metadata_calc_len;
-        save_last_lblock = ei->i_da_metadata_calc_last_lblock;
-        md_needed = EXT4_NUM_B2C(sbi,
-                                 ext4_calc_metadata_amount(inode, lblock));
-        trace_ext4_da_reserve_space(inode, md_needed);
-
-        /*
-         * We do still charge estimated metadata to the sb though;
-         * we cannot afford to run out of free blocks.
-         */
-        if (ext4_claim_free_clusters(sbi, md_needed, 0)) {
-                ei->i_da_metadata_calc_len = save_len;
-                ei->i_da_metadata_calc_last_lblock = save_last_lblock;
-                spin_unlock(&ei->i_block_reservation_lock);
-                return -ENOSPC;
-        }
-        ei->i_reserved_meta_blocks += md_needed;
-        spin_unlock(&ei->i_block_reservation_lock);
-
-        return 0;       /* success */
-}
-
-/*
  * Reserve a single cluster located at lblock
  */
 static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
@@ -1273,8 +1193,6 @@ static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
         struct ext4_inode_info *ei = EXT4_I(inode);
         unsigned int md_needed;
         int ret;
-        ext4_lblk_t save_last_lblock;
-        int save_len;
 
         /*
          * We will charge metadata quota at writeout time; this saves
@@ -1295,25 +1213,15 @@ static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
          * ext4_calc_metadata_amount() has side effects, which we have
          * to be prepared undo if we fail to claim space.
          */
-        save_len = ei->i_da_metadata_calc_len;
-        save_last_lblock = ei->i_da_metadata_calc_last_lblock;
-        md_needed = EXT4_NUM_B2C(sbi,
-                                 ext4_calc_metadata_amount(inode, lblock));
-        trace_ext4_da_reserve_space(inode, md_needed);
+        md_needed = 0;
+        trace_ext4_da_reserve_space(inode, 0);
 
-        /*
-         * We do still charge estimated metadata to the sb though;
-         * we cannot afford to run out of free blocks.
-         */
-        if (ext4_claim_free_clusters(sbi, md_needed + 1, 0)) {
-                ei->i_da_metadata_calc_len = save_len;
-                ei->i_da_metadata_calc_last_lblock = save_last_lblock;
+        if (ext4_claim_free_clusters(sbi, 1, 0)) {
                 spin_unlock(&ei->i_block_reservation_lock);
                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
                 return -ENOSPC;
         }
         ei->i_reserved_data_blocks++;
-        ei->i_reserved_meta_blocks += md_needed;
         spin_unlock(&ei->i_block_reservation_lock);
 
         return 0;       /* success */
@@ -1346,20 +1254,6 @@ static void ext4_da_release_space(struct inode *inode, int to_free)
         }
         ei->i_reserved_data_blocks -= to_free;
 
-        if (ei->i_reserved_data_blocks == 0) {
-                /*
-                 * We can release all of the reserved metadata blocks
-                 * only when we have written all of the delayed
-                 * allocation blocks.
-                 * Note that in case of bigalloc, i_reserved_meta_blocks,
-                 * i_reserved_data_blocks, etc. refer to number of clusters.
-                 */
-                percpu_counter_sub(&sbi->s_dirtyclusters_counter,
-                                   ei->i_reserved_meta_blocks);
-                ei->i_reserved_meta_blocks = 0;
-                ei->i_da_metadata_calc_len = 0;
-        }
-
         /* update fs dirty data blocks counter */
         percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
 
@@ -1500,10 +1394,6 @@ static void ext4_print_free_blocks(struct inode *inode)
         ext4_msg(sb, KERN_CRIT, "Block reservation details");
         ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
                  ei->i_reserved_data_blocks);
-        ext4_msg(sb, KERN_CRIT, "i_reserved_meta_blocks=%u",
-               ei->i_reserved_meta_blocks);
-        ext4_msg(sb, KERN_CRIT, "i_allocated_meta_blocks=%u",
-               ei->i_allocated_meta_blocks);
         return;
 }
 
@@ -1620,13 +1510,6 @@ add_delayed:
                                 retval = ret;
                                 goto out_unlock;
                         }
-                } else {
-                        ret = ext4_da_reserve_metadata(inode, iblock);
-                        if (ret) {
-                                /* not enough space to reserve */
-                                retval = ret;
-                                goto out_unlock;
-                        }
                 }
 
                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
@@ -2843,8 +2726,7 @@ int ext4_alloc_da_blocks(struct inode *inode)
 {
         trace_ext4_alloc_da_blocks(inode);
 
-        if (!EXT4_I(inode)->i_reserved_data_blocks &&
-            !EXT4_I(inode)->i_reserved_meta_blocks)
+        if (!EXT4_I(inode)->i_reserved_data_blocks)
                 return 0;
 
         /*
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 2dcb936be90e..18a16191249a 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4627,7 +4627,6 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
         struct buffer_head *gd_bh;
         ext4_group_t block_group;
         struct ext4_sb_info *sbi;
-        struct ext4_inode_info *ei = EXT4_I(inode);
         struct ext4_buddy e4b;
         unsigned int count_clusters;
         int err = 0;
@@ -4838,19 +4837,7 @@ do_more:
                              &sbi->s_flex_groups[flex_group].free_clusters);
         }
 
-        if (flags & EXT4_FREE_BLOCKS_RESERVE && ei->i_reserved_data_blocks) {
-                percpu_counter_add(&sbi->s_dirtyclusters_counter,
-                                   count_clusters);
-                spin_lock(&ei->i_block_reservation_lock);
-                if (flags & EXT4_FREE_BLOCKS_METADATA)
-                        ei->i_reserved_meta_blocks += count_clusters;
-                else
-                        ei->i_reserved_data_blocks += count_clusters;
-                spin_unlock(&ei->i_block_reservation_lock);
-                if (!(flags & EXT4_FREE_BLOCKS_NO_QUOT_UPDATE))
-                        dquot_reclaim_block(inode,
-                                        EXT4_C2B(sbi, count_clusters));
-        } else if (!(flags & EXT4_FREE_BLOCKS_NO_QUOT_UPDATE))
+        if (!(flags & EXT4_FREE_BLOCKS_NO_QUOT_UPDATE))
                 dquot_free_block(inode, EXT4_C2B(sbi, count_clusters));
         percpu_counter_add(&sbi->s_freeclusters_counter, count_clusters);