ext4: Invert lock ordering of page_lock and transaction start in delalloc

With the reverse locking, we need to start a transation before taking
the page lock, so in ext4_da_writepages() we need to break the write-out
into chunks, and restart the journal for each chunck to ensure the
write-out fits in a single transaction.

Updated patch from Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
which fixes delalloc sync hang with journal lock inversion, and address
the performance regression issue.

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 8 insertions, 2 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index dabc3b68d249..42c4c0c892ed 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2565,6 +2565,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
         int err = 0, depth, ret;
         unsigned long allocated = 0;
         struct ext4_allocation_request ar;
+        loff_t disksize;
 
         __clear_bit(BH_New, &bh_result->b_state);
         ext_debug("blocks %u/%lu requested for inode %u\n",
@@ -2755,8 +2756,13 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
         newblock = ext_pblock(&newex);
         allocated = ext4_ext_get_actual_len(&newex);
 outnew:
-        if (extend_disksize && inode->i_size > EXT4_I(inode)->i_disksize)
-                EXT4_I(inode)->i_disksize = inode->i_size;
+        if (extend_disksize) {
+                disksize = ((loff_t) iblock + ar.len) << inode->i_blkbits;
+                if (disksize > i_size_read(inode))
+                        disksize = i_size_read(inode);
+                if (disksize > EXT4_I(inode)->i_disksize)
+                        EXT4_I(inode)->i_disksize = disksize;
+        }
 
         set_buffer_new(bh_result);