1 files changed, 321 insertions, 157 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 59fbbe899acc..7e91913e325b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -41,6 +41,8 @@
 #include "acl.h"
 #include "ext4_extents.h"
 
+#define MPAGE_DA_EXTENT_TAIL 0x01
+
 static inline int ext4_begin_ordered_truncate(struct inode *inode,
                                               loff_t new_size)
 {
@@ -1005,6 +1007,9 @@ static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
  */
 static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
 {
+        if (!blocks)
+                return 0;
+
         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
                 return ext4_ext_calc_metadata_amount(inode, blocks);
 
@@ -1041,18 +1046,6 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
         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
-/*
- * Number of credits we need for writing DIO_MAX_BLOCKS:
- * We need sb + group descriptor + bitmap + inode -> 4
- * For B blocks with A block pointers per block we need:
- * 1 (triple ind.) + (B/A/A + 2) (doubly ind.) + (B/A + 2) (indirect).
- * If we plug in 4096 for B and 256 for A (for 1KB block size), we get 25.
- */
-#define DIO_CREDITS 25
-
-
 /*
  * The ext4_get_blocks_wrap() function try to look up the requested blocks,
  * and returns if the blocks are already mapped.
@@ -1164,19 +1157,23 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
         return retval;
 }
 
+/* Maximum number of blocks we map for direct IO at once. */
+#define DIO_MAX_BLOCKS 4096
+
 static int ext4_get_block(struct inode *inode, sector_t iblock,
                         struct buffer_head *bh_result, int create)
 {
         handle_t *handle = ext4_journal_current_handle();
         int ret = 0, started = 0;
         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
+        int dio_credits;
 
         if (create && !handle) {
                 /* Direct IO write... */
                 if (max_blocks > DIO_MAX_BLOCKS)
                         max_blocks = DIO_MAX_BLOCKS;
-                handle = ext4_journal_start(inode, DIO_CREDITS +
-                              2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
+                dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
+                handle = ext4_journal_start(inode, dio_credits);
                 if (IS_ERR(handle)) {
                         ret = PTR_ERR(handle);
                         goto out;
@@ -1559,7 +1556,25 @@ 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;
 
+        if (!to_free)
+                return;         /* Nothing to release, exit */
+
         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
+
+        if (!EXT4_I(inode)->i_reserved_data_blocks) {
+                /*
+                 * if there is no reserved blocks, but we try to free some
+                 * then the counter is messed up somewhere.
+                 * but since this function is called from invalidate
+                 * page, it's harmless to return without any action
+                 */
+                printk(KERN_INFO "ext4 delalloc try to release %d reserved "
+                            "blocks for inode %lu, but there is no reserved "
+                            "data blocks\n", to_free, inode->i_ino);
+                spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+                return;
+        }
+
         /* recalculate the number of metablocks still need to be reserved */
         total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
         mdb = ext4_calc_metadata_amount(inode, total);
@@ -1613,11 +1628,13 @@ struct mpage_da_data {
         unsigned long first_page, next_page;    /* extent of pages */
         get_block_t *get_block;
         struct writeback_control *wbc;
+        int io_done;
+        long pages_written;
 };
 
 /*
  * mpage_da_submit_io - walks through extent of pages and try to write
- * them with __mpage_writepage()
+ * them with writepage() call back
  *
  * @mpd->inode: inode
  * @mpd->first_page: first page of the extent
@@ -1632,18 +1649,11 @@ struct mpage_da_data {
 static int mpage_da_submit_io(struct mpage_da_data *mpd)
 {
         struct address_space *mapping = mpd->inode->i_mapping;
-        struct mpage_data mpd_pp = {
-                .bio = NULL,
-                .last_block_in_bio = 0,
-                .get_block = mpd->get_block,
-                .use_writepage = 1,
-        };
         int ret = 0, err, nr_pages, i;
         unsigned long index, end;
         struct pagevec pvec;
 
         BUG_ON(mpd->next_page <= mpd->first_page);
-
         pagevec_init(&pvec, 0);
         index = mpd->first_page;
         end = mpd->next_page - 1;
@@ -1661,8 +1671,9 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
                                 break;
                         index++;
 
-                        err = __mpage_writepage(page, mpd->wbc, &mpd_pp);
-
+                        err = mapping->a_ops->writepage(page, mpd->wbc);
+                        if (!err)
+                                mpd->pages_written++;
                         /*
                          * In error case, we have to continue because
                          * remaining pages are still locked
@@ -1673,9 +1684,6 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
                 }
                 pagevec_release(&pvec);
         }
-        if (mpd_pp.bio)
-                mpage_bio_submit(WRITE, mpd_pp.bio);
-
         return ret;
 }
 
@@ -1698,7 +1706,7 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
         int blocks = exbh->b_size >> inode->i_blkbits;
         sector_t pblock = exbh->b_blocknr, cur_logical;
         struct buffer_head *head, *bh;
-        unsigned long index, end;
+        pgoff_t index, end;
         struct pagevec pvec;
         int nr_pages, i;
 
@@ -1741,6 +1749,13 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
                                 if (buffer_delay(bh)) {
                                         bh->b_blocknr = pblock;
                                         clear_buffer_delay(bh);
+                                        bh->b_bdev = inode->i_sb->s_bdev;
+                                } else if (buffer_unwritten(bh)) {
+                                        bh->b_blocknr = pblock;
+                                        clear_buffer_unwritten(bh);
+                                        set_buffer_mapped(bh);
+                                        set_buffer_new(bh);
+                                        bh->b_bdev = inode->i_sb->s_bdev;
                                 } else if (buffer_mapped(bh))
                                         BUG_ON(bh->b_blocknr != pblock);
 
@@ -1776,13 +1791,11 @@ static inline void __unmap_underlying_blocks(struct inode *inode,
  *
  * The function skips space we know is already mapped to disk blocks.
  *
- * The function ignores errors ->get_block() returns, thus real
- * error handling is postponed to __mpage_writepage()
  */
 static void mpage_da_map_blocks(struct mpage_da_data *mpd)
 {
+        int err = 0;
         struct buffer_head *lbh = &mpd->lbh;
-        int err = 0, remain = lbh->b_size;
         sector_t next = lbh->b_blocknr;
         struct buffer_head new;
 
@@ -1792,38 +1805,36 @@ static void mpage_da_map_blocks(struct mpage_da_data *mpd)
         if (buffer_mapped(lbh) && !buffer_delay(lbh))
                 return;
 
-        while (remain) {
-                new.b_state = lbh->b_state;
-                new.b_blocknr = 0;
-                new.b_size = remain;
-                err = mpd->get_block(mpd->inode, next, &new, 1);
-                if (err) {
-                        /*
-                         * Rather than implement own error handling
-                         * here, we just leave remaining blocks
-                         * unallocated and try again with ->writepage()
-                         */
-                        break;
-                }
-                BUG_ON(new.b_size == 0);
+        new.b_state = lbh->b_state;
+        new.b_blocknr = 0;
+        new.b_size = lbh->b_size;
 
-                if (buffer_new(&new))
-                        __unmap_underlying_blocks(mpd->inode, &new);
+        /*
+         * If we didn't accumulate anything
+         * to write simply return
+         */
+        if (!new.b_size)
+                return;
+        err = mpd->get_block(mpd->inode, next, &new, 1);
+        if (err)
+                return;
+        BUG_ON(new.b_size == 0);
 
-                /*
-                 * If blocks are delayed marked, we need to
-                 * put actual blocknr and drop delayed bit
-                 */
-                if (buffer_delay(lbh))
-                        mpage_put_bnr_to_bhs(mpd, next, &new);
+        if (buffer_new(&new))
+                __unmap_underlying_blocks(mpd->inode, &new);
 
-                /* go for the remaining blocks */
-                next += new.b_size >> mpd->inode->i_blkbits;
-                remain -= new.b_size;
-        }
+        /*
+         * If blocks are delayed marked, we need to
+         * put actual blocknr and drop delayed bit
+         */
+        if (buffer_delay(lbh) || buffer_unwritten(lbh))
+                mpage_put_bnr_to_bhs(mpd, next, &new);
+
+        return;
 }
 
-#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | (1 << BH_Delay))
+#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
+                (1 << BH_Delay) | (1 << BH_Unwritten))
 
 /*
  * mpage_add_bh_to_extent - try to add one more block to extent of blocks
@@ -1837,41 +1848,61 @@ static void mpage_da_map_blocks(struct mpage_da_data *mpd)
 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
                                    sector_t logical, struct buffer_head *bh)
 {
-        struct buffer_head *lbh = &mpd->lbh;
         sector_t next;
+        size_t b_size = bh->b_size;
+        struct buffer_head *lbh = &mpd->lbh;
+        int nrblocks = lbh->b_size >> mpd->inode->i_blkbits;
 
-        next = lbh->b_blocknr + (lbh->b_size >> mpd->inode->i_blkbits);
-
+        /* check if thereserved journal credits might overflow */
+        if (!(EXT4_I(mpd->inode)->i_flags & EXT4_EXTENTS_FL)) {
+                if (nrblocks >= EXT4_MAX_TRANS_DATA) {
+                        /*
+                         * With non-extent format we are limited by the journal
+                         * credit available.  Total credit needed to insert
+                         * nrblocks contiguous blocks is dependent on the
+                         * nrblocks.  So limit nrblocks.
+                         */
+                        goto flush_it;
+                } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
+                                EXT4_MAX_TRANS_DATA) {
+                        /*
+                         * Adding the new buffer_head would make it cross the
+                         * allowed limit for which we have journal credit
+                         * reserved. So limit the new bh->b_size
+                         */
+                        b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
+                                                mpd->inode->i_blkbits;
+                        /* we will do mpage_da_submit_io in the next loop */
+                }
+        }
         /*
          * First block in the extent
          */
         if (lbh->b_size == 0) {
                 lbh->b_blocknr = logical;
-                lbh->b_size = bh->b_size;
+                lbh->b_size = b_size;
                 lbh->b_state = bh->b_state & BH_FLAGS;
                 return;
         }
 
+        next = lbh->b_blocknr + nrblocks;
         /*
          * Can we merge the block to our big extent?
          */
         if (logical == next && (bh->b_state & BH_FLAGS) == lbh->b_state) {
-                lbh->b_size += bh->b_size;
+                lbh->b_size += b_size;
                 return;
         }
 
+flush_it:
         /*
          * We couldn't merge the block to our extent, so we
          * need to flush current  extent and start new one
          */
         mpage_da_map_blocks(mpd);
-
-        /*
-         * Now start a new extent
-         */
-        lbh->b_size = bh->b_size;
-        lbh->b_state = bh->b_state & BH_FLAGS;
-        lbh->b_blocknr = logical;
+        mpage_da_submit_io(mpd);
+        mpd->io_done = 1;
+        return;
 }
 
 /*
@@ -1891,17 +1922,35 @@ static int __mpage_da_writepage(struct page *page,
         struct buffer_head *bh, *head, fake;
         sector_t logical;
 
+        if (mpd->io_done) {
+                /*
+                 * Rest of the page in the page_vec
+                 * redirty then and skip then. We will
+                 * try to to write them again after
+                 * starting a new transaction
+                 */
+                redirty_page_for_writepage(wbc, page);
+                unlock_page(page);
+                return MPAGE_DA_EXTENT_TAIL;
+        }
         /*
          * Can we merge this page to current extent?
          */
         if (mpd->next_page != page->index) {
                 /*
                  * Nope, we can't. So, we map non-allocated blocks
-                 * and start IO on them using __mpage_writepage()
+                 * and start IO on them using writepage()
                  */
                 if (mpd->next_page != mpd->first_page) {
                         mpage_da_map_blocks(mpd);
                         mpage_da_submit_io(mpd);
+                        /*
+                         * skip rest of the page in the page_vec
+                         */
+                        mpd->io_done = 1;
+                        redirty_page_for_writepage(wbc, page);
+                        unlock_page(page);
+                        return MPAGE_DA_EXTENT_TAIL;
                 }
 
                 /*
@@ -1932,6 +1981,8 @@ static int __mpage_da_writepage(struct page *page,
                 set_buffer_dirty(bh);
                 set_buffer_uptodate(bh);
                 mpage_add_bh_to_extent(mpd, logical, bh);
+                if (mpd->io_done)
+                        return MPAGE_DA_EXTENT_TAIL;
         } else {
                 /*
                  * Page with regular buffer heads, just add all dirty ones
@@ -1940,8 +1991,12 @@ static int __mpage_da_writepage(struct page *page,
                 bh = head;
                 do {
                         BUG_ON(buffer_locked(bh));
-                        if (buffer_dirty(bh))
+                        if (buffer_dirty(bh) &&
+                                (!buffer_mapped(bh) || buffer_delay(bh))) {
                                 mpage_add_bh_to_extent(mpd, logical, bh);
+                                if (mpd->io_done)
+                                        return MPAGE_DA_EXTENT_TAIL;
+                        }
                         logical++;
                 } while ((bh = bh->b_this_page) != head);
         }
@@ -1960,22 +2015,13 @@ static int __mpage_da_writepage(struct page *page,
  *
  * This is a library function, which implements the writepages()
  * address_space_operation.
- *
- * In order to avoid duplication of logic that deals with partial pages,
- * multiple bio per page, etc, we find non-allocated blocks, allocate
- * them with minimal calls to ->get_block() and re-use __mpage_writepage()
- *
- * It's important that we call __mpage_writepage() only once for each
- * involved page, otherwise we'd have to implement more complicated logic
- * to deal with pages w/o PG_lock or w/ PG_writeback and so on.
- *
- * See comments to mpage_writepages()
  */
 static int mpage_da_writepages(struct address_space *mapping,
                                struct writeback_control *wbc,
                                get_block_t get_block)
 {
         struct mpage_da_data mpd;
+        long to_write;
         int ret;
 
         if (!get_block)
@@ -1989,17 +2035,22 @@ static int mpage_da_writepages(struct address_space *mapping,
         mpd.first_page = 0;
         mpd.next_page = 0;
         mpd.get_block = get_block;
+        mpd.io_done = 0;
+        mpd.pages_written = 0;
+
+        to_write = wbc->nr_to_write;
 
         ret = write_cache_pages(mapping, wbc, __mpage_da_writepage, &mpd);
 
         /*
          * Handle last extent of pages
          */
-        if (mpd.next_page != mpd.first_page) {
+        if (!mpd.io_done && mpd.next_page != mpd.first_page) {
                 mpage_da_map_blocks(&mpd);
                 mpage_da_submit_io(&mpd);
         }
 
+        wbc->nr_to_write = to_write - mpd.pages_written;
         return ret;
 }
 
@@ -2204,63 +2255,95 @@ static int ext4_da_writepage(struct page *page,
 }
 
 /*
- * For now just follow the DIO way to estimate the max credits
- * needed to write out EXT4_MAX_WRITEBACK_PAGES.
- * todo: need to calculate the max credits need for
- * extent based files, currently the DIO credits is based on
- * indirect-blocks mapping way.
- *
- * Probably should have a generic way to calculate credits
- * for DIO, writepages, and truncate
+ * This is called via ext4_da_writepages() to
+ * calulate the total number of credits to reserve to fit
+ * a single extent allocation into a single transaction,
+ * ext4_da_writpeages() will loop calling this before
+ * the block allocation.
  */
-#define EXT4_MAX_WRITEBACK_PAGES      DIO_MAX_BLOCKS
-#define EXT4_MAX_WRITEBACK_CREDITS    DIO_CREDITS
+
+static int ext4_da_writepages_trans_blocks(struct inode *inode)
+{
+        int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
+
+        /*
+         * With non-extent format the journal credit needed to
+         * insert nrblocks contiguous block is dependent on
+         * number of contiguous block. So we will limit
+         * number of contiguous block to a sane value
+         */
+        if (!(inode->i_flags & EXT4_EXTENTS_FL) &&
+            (max_blocks > EXT4_MAX_TRANS_DATA))
+                max_blocks = EXT4_MAX_TRANS_DATA;
+
+        return ext4_chunk_trans_blocks(inode, max_blocks);
+}
 
 static int ext4_da_writepages(struct address_space *mapping,
-                                struct writeback_control *wbc)
+                              struct writeback_control *wbc)
 {
-        struct inode *inode = mapping->host;
         handle_t *handle = NULL;
-        int needed_blocks;
-        int ret = 0;
-        long to_write;
         loff_t range_start = 0;
+        struct inode *inode = mapping->host;
+        int needed_blocks, ret = 0, nr_to_writebump = 0;
+        long to_write, pages_skipped = 0;
+        struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
 
         /*
          * No pages to write? This is mainly a kludge to avoid starting
          * a transaction for special inodes like journal inode on last iput()
          * because that could violate lock ordering on umount
          */
-        if (!mapping->nrpages)
+        if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
                 return 0;
-
         /*
-         * Estimate the worse case needed credits to write out
-         * EXT4_MAX_BUF_BLOCKS pages
+         * Make sure nr_to_write is >= sbi->s_mb_stream_request
+         * This make sure small files blocks are allocated in
+         * single attempt. This ensure that small files
+         * get less fragmented.
          */
-        needed_blocks = EXT4_MAX_WRITEBACK_CREDITS;
+        if (wbc->nr_to_write < sbi->s_mb_stream_request) {
+                nr_to_writebump = sbi->s_mb_stream_request - wbc->nr_to_write;
+                wbc->nr_to_write = sbi->s_mb_stream_request;
+        }
 
-        to_write = wbc->nr_to_write;
-        if (!wbc->range_cyclic) {
+        if (!wbc->range_cyclic)
                 /*
                  * If range_cyclic is not set force range_cont
                  * and save the old writeback_index
                  */
                 wbc->range_cont = 1;
-                range_start =  wbc->range_start;
-        }
 
-        while (!ret && to_write) {
+        range_start =  wbc->range_start;
+        pages_skipped = wbc->pages_skipped;
+
+restart_loop:
+        to_write = wbc->nr_to_write;
+        while (!ret && to_write > 0) {
+
+                /*
+                 * we  insert one extent at a time. So we need
+                 * credit needed for single extent allocation.
+                 * journalled mode is currently not supported
+                 * by delalloc
+                 */
+                BUG_ON(ext4_should_journal_data(inode));
+                needed_blocks = ext4_da_writepages_trans_blocks(inode);
+
                 /* start a new transaction*/
                 handle = ext4_journal_start(inode, needed_blocks);
                 if (IS_ERR(handle)) {
                         ret = PTR_ERR(handle);
+                        printk(KERN_EMERG "%s: jbd2_start: "
+                               "%ld pages, ino %lu; err %d\n", __func__,
+                                wbc->nr_to_write, inode->i_ino, ret);
+                        dump_stack();
                         goto out_writepages;
                 }
                 if (ext4_should_order_data(inode)) {
                         /*
                          * With ordered mode we need to add
-                         * the inode to the journal handle
+                         * the inode to the journal handl
                          * when we do block allocation.
                          */
                         ret = ext4_jbd2_file_inode(handle, inode);
@@ -2268,20 +2351,20 @@ static int ext4_da_writepages(struct address_space *mapping,
                                 ext4_journal_stop(handle);
                                 goto out_writepages;
                         }
-
                 }
-                /*
-                 * set the max dirty pages could be write at a time
-                 * to fit into the reserved transaction credits
-                 */
-                if (wbc->nr_to_write > EXT4_MAX_WRITEBACK_PAGES)
-                        wbc->nr_to_write = EXT4_MAX_WRITEBACK_PAGES;
 
                 to_write -= wbc->nr_to_write;
                 ret = mpage_da_writepages(mapping, wbc,
-                                                ext4_da_get_block_write);
+                                          ext4_da_get_block_write);
                 ext4_journal_stop(handle);
-                if (wbc->nr_to_write) {
+                if (ret == MPAGE_DA_EXTENT_TAIL) {
+                        /*
+                         * got one extent now try with
+                         * rest of the pages
+                         */
+                        to_write += wbc->nr_to_write;
+                        ret = 0;
+                } else if (wbc->nr_to_write) {
                         /*
                          * There is no more writeout needed
                          * or we requested for a noblocking writeout
@@ -2293,10 +2376,18 @@ static int ext4_da_writepages(struct address_space *mapping,
                 wbc->nr_to_write = to_write;
         }
 
-out_writepages:
-        wbc->nr_to_write = to_write;
-        if (range_start)
+        if (wbc->range_cont && (pages_skipped != wbc->pages_skipped)) {
+                /* We skipped pages in this loop */
                 wbc->range_start = range_start;
+                wbc->nr_to_write = to_write +
+                                wbc->pages_skipped - pages_skipped;
+                wbc->pages_skipped = pages_skipped;
+                goto restart_loop;
+        }
+
+out_writepages:
+        wbc->nr_to_write = to_write - nr_to_writebump;
+        wbc->range_start = range_start;
         return ret;
 }
 
@@ -3486,6 +3577,9 @@ void ext4_truncate(struct inode *inode)
          * modify the block allocation tree.
          */
         down_write(&ei->i_data_sem);
+
+        ext4_discard_reservation(inode);
+
         /*
          * The orphan list entry will now protect us from any crash which
          * occurs before the truncate completes, so it is now safe to propagate
@@ -3555,8 +3649,6 @@ do_indirects:
                 ;
         }
 
-        ext4_discard_reservation(inode);
-
         up_write(&ei->i_data_sem);
         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
         ext4_mark_inode_dirty(handle, inode);
@@ -4324,57 +4416,129 @@ int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
         return 0;
 }
 
+static int ext4_indirect_trans_blocks(struct inode *inode, int nrblocks,
+                                      int chunk)
+{
+        int indirects;
+
+        /* if nrblocks are contiguous */
+        if (chunk) {
+                /*
+                 * With N contiguous data blocks, it need at most
+                 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks
+                 * 2 dindirect blocks
+                 * 1 tindirect block
+                 */
+                indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb);
+                return indirects + 3;
+        }
+        /*
+         * if nrblocks are not contiguous, worse case, each block touch
+         * a indirect block, and each indirect block touch a double indirect
+         * block, plus a triple indirect block
+         */
+        indirects = nrblocks * 2 + 1;
+        return indirects;
+}
+
+static int ext4_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
+{
+        if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+                return ext4_indirect_trans_blocks(inode, nrblocks, 0);
+        return ext4_ext_index_trans_blocks(inode, nrblocks, 0);
+}
 /*
- * How many blocks doth make a writepage()?
- *
- * With N blocks per page, it may be:
- * N data blocks
- * 2 indirect block
- * 2 dindirect
- * 1 tindirect
- * N+5 bitmap blocks (from the above)
- * N+5 group descriptor summary blocks
- * 1 inode block
- * 1 superblock.
- * 2 * EXT4_SINGLEDATA_TRANS_BLOCKS for the quote files
+ * Account for index blocks, block groups bitmaps and block group
+ * descriptor blocks if modify datablocks and index blocks
+ * worse case, the indexs blocks spread over different block groups
  *
- * 3 * (N + 5) + 2 + 2 * EXT4_SINGLEDATA_TRANS_BLOCKS
+ * If datablocks are discontiguous, they are possible to spread over
+ * different block groups too. If they are contiugous, with flexbg,
+ * they could still across block group boundary.
  *
- * With ordered or writeback data it's the same, less the N data blocks.
+ * Also account for superblock, inode, quota and xattr blocks
+ */
+int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
+{
+        int groups, gdpblocks;
+        int idxblocks;
+        int ret = 0;
+
+        /*
+         * How many index blocks need to touch to modify nrblocks?
+         * The "Chunk" flag indicating whether the nrblocks is
+         * physically contiguous on disk
+         *
+         * For Direct IO and fallocate, they calls get_block to allocate
+         * one single extent at a time, so they could set the "Chunk" flag
+         */
+        idxblocks = ext4_index_trans_blocks(inode, nrblocks, chunk);
+
+        ret = idxblocks;
+
+        /*
+         * Now let's see how many group bitmaps and group descriptors need
+         * to account
+         */
+        groups = idxblocks;
+        if (chunk)
+                groups += 1;
+        else
+                groups += nrblocks;
+
+        gdpblocks = groups;
+        if (groups > EXT4_SB(inode->i_sb)->s_groups_count)
+                groups = EXT4_SB(inode->i_sb)->s_groups_count;
+        if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
+                gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
+
+        /* bitmaps and block group descriptor blocks */
+        ret += groups + gdpblocks;
+
+        /* Blocks for super block, inode, quota and xattr blocks */
+        ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
+
+        return ret;
+}
+
+/*
+ * Calulate the total number of credits to reserve to fit
+ * the modification of a single pages into a single transaction,
+ * which may include multiple chunks of block allocations.
  *
- * If the inode's direct blocks can hold an integral number of pages then a
- * page cannot straddle two indirect blocks, and we can only touch one indirect
- * and dindirect block, and the "5" above becomes "3".
+ * This could be called via ext4_write_begin()
  *
- * This still overestimates under most circumstances.  If we were to pass the
- * start and end offsets in here as well we could do block_to_path() on each
- * block and work out the exact number of indirects which are touched.  Pah.
+ * We need to consider the worse case, when
+ * one new block per extent.
  */
-
 int ext4_writepage_trans_blocks(struct inode *inode)
 {
         int bpp = ext4_journal_blocks_per_page(inode);
-        int indirects = (EXT4_NDIR_BLOCKS % bpp) ? 5 : 3;
         int ret;
 
-        if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
-                return ext4_ext_writepage_trans_blocks(inode, bpp);
+        ret = ext4_meta_trans_blocks(inode, bpp, 0);
 
+        /* Account for data blocks for journalled mode */
         if (ext4_should_journal_data(inode))
-                ret = 3 * (bpp + indirects) + 2;
-        else
-                ret = 2 * (bpp + indirects) + 2;
-
-#ifdef CONFIG_QUOTA
-        /* We know that structure was already allocated during DQUOT_INIT so
-         * we will be updating only the data blocks + inodes */
-        ret += 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
-#endif
-
+                ret += bpp;
         return ret;
 }
 
 /*
+ * Calculate the journal credits for a chunk of data modification.
+ *
+ * This is called from DIO, fallocate or whoever calling
+ * ext4_get_blocks_wrap() to map/allocate a chunk of contigous disk blocks.
+ *
+ * journal buffers for data blocks are not included here, as DIO
+ * and fallocate do no need to journal data buffers.
+ */
+int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
+{
+        return ext4_meta_trans_blocks(inode, nrblocks, 1);
+}
+
+/*
  * The caller must have previously called ext4_reserve_inode_write().
  * Give this, we know that the caller already has write access to iloc->bh.
  */