Re: [PATCH v3]Ext4: journal credits reservation fixes for DIO, fallocate and delalloc writepages
From: Mingming Cao <hidden>
Date: 2008-08-01 18:03:17
Ted, thanks for going through this, 在 2008-08-01五的 01:49 -0400，Theodore Tso写道：
ext4: Fix lack of credits BUG() when deleting a badly fragmented inode
The extents codepath for ext4_truncate() requests journal transaction
credits in very small chunks, requesting only what is needed. This
means there may not be enough credits left on the transaction handle
after ext4_truncate() returns and then when ext4_delete_inode() tries
finish up its work, it may not have enough transaction credits,
causing a BUG() oops in the jbd2 core.But, ext4_delete_inode()'s transaction and ext4_truncate()'s transaction are different, ext4_truncate() transaction is nested inside ext4_delete_inode. Inside ext4_delete_inode, the transaction is to log the changes in ext4_orhan_del() and ext4_free_inode(). If I get right, ext4_orhan_del() need credit to modify superblock and inode block, ext4_free_inode() needs credit for modifying quota,xattr and inode bitmap, group descriptor, superblock, and inode block. Currently ext4_delete_inode() uses blocks_for_truncate(inode) to calculate credits, by the time ext4_delete_inode() is called, i_blocks seems to 0 (I need to double check this). So the credits is just EXT4_DATA_TRANS_BLOCKS, which take care of the credits for inode, superblock, xattr and quota, but missing is inode bitmap...I will double check before I post a patch...
quoted hunk ↗ jump to hunk
Signed-off-by: "Theodore Ts'o" [off-list ref]diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c7fb647..6d27e78 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c@@ -215,6 +215,18 @@ void ext4_delete_inode (struct inode * inode) inode->i_size = 0; if (inode->i_blocks) ext4_truncate(inode); + + /* + * ext4_ext_truncate() doesn't reserve any slop when it + * restarts journal transactions; therefore there may not be + * enough credits left in the handle to remove the inode from + * the orphan list and set the dtime field. + */ + if (ext4_ext_journal_restart(handle, 3)) { + ext4_journal_stop(handle); + goto no_delete; + } + /* * Kill off the orphan record which ext4_truncate created. * AKPM: I think this can be inside the above `if'.
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