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>
This commit is contained in:
Mingming Cao
Theodore Ts'o
parent
06d6cf6959
commit
61628a3f3a
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@ -2565,6 +2565,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
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int err = 0, depth, ret;
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unsigned long allocated = 0;
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struct ext4_allocation_request ar;
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loff_t disksize;
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__clear_bit(BH_New, &bh_result->b_state);
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ext_debug("blocks %u/%lu requested for inode %u\n",
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@ -2755,8 +2756,13 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
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newblock = ext_pblock(&newex);
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allocated = ext4_ext_get_actual_len(&newex);
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outnew:
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if (extend_disksize && inode->i_size > EXT4_I(inode)->i_disksize)
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EXT4_I(inode)->i_disksize = inode->i_size;
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if (extend_disksize) {
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disksize = ((loff_t) iblock + ar.len) << inode->i_blkbits;
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if (disksize > i_size_read(inode))
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disksize = i_size_read(inode);
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if (disksize > EXT4_I(inode)->i_disksize)
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EXT4_I(inode)->i_disksize = disksize;
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}
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set_buffer_new(bh_result);
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201
fs/ext4/inode.c
201
fs/ext4/inode.c
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@ -847,6 +847,7 @@ int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
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struct ext4_inode_info *ei = EXT4_I(inode);
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int count = 0;
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ext4_fsblk_t first_block = 0;
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loff_t disksize;
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J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
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@ -922,8 +923,13 @@ int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
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* protect it if you're about to implement concurrent
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* ext4_get_block() -bzzz
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*/
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if (!err && extend_disksize && inode->i_size > ei->i_disksize)
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ei->i_disksize = inode->i_size;
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if (!err && extend_disksize) {
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disksize = ((loff_t) iblock + count) << inode->i_blkbits;
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if (disksize > i_size_read(inode))
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disksize = i_size_read(inode);
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if (disksize > ei->i_disksize)
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ei->i_disksize = disksize;
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}
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if (err)
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goto cleanup;
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@ -1683,13 +1689,11 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
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do {
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if (cur_logical >= logical + blocks)
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break;
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if (buffer_delay(bh)) {
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bh->b_blocknr = pblock;
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clear_buffer_delay(bh);
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} else if (buffer_mapped(bh)) {
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} else if (buffer_mapped(bh))
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BUG_ON(bh->b_blocknr != pblock);
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}
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cur_logical++;
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pblock++;
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@ -1764,10 +1768,10 @@ static void mpage_da_map_blocks(struct mpage_da_data *mpd)
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if (buffer_delay(lbh))
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mpage_put_bnr_to_bhs(mpd, next, &new);
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/* go for the remaining blocks */
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next += new.b_size >> mpd->inode->i_blkbits;
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remain -= new.b_size;
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}
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/* go for the remaining blocks */
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next += new.b_size >> mpd->inode->i_blkbits;
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remain -= new.b_size;
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}
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}
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#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | (1 << BH_Delay))
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@ -1993,18 +1997,14 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
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static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
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struct buffer_head *bh_result, int create)
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{
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int ret, needed_blocks = ext4_writepage_trans_blocks(inode);
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int ret;
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unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
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loff_t disksize = EXT4_I(inode)->i_disksize;
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handle_t *handle = NULL;
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if (create) {
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handle = ext4_journal_start(inode, needed_blocks);
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if (IS_ERR(handle)) {
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ret = PTR_ERR(handle);
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goto out;
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}
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}
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handle = ext4_journal_current_handle();
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BUG_ON(handle == NULL);
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BUG_ON(create == 0);
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ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
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bh_result, create, 0, EXT4_DELALLOC_RSVED);
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@ -2029,65 +2029,157 @@ static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
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up_write(&EXT4_I(inode)->i_data_sem);
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if (EXT4_I(inode)->i_disksize == disksize) {
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if (handle == NULL)
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handle = ext4_journal_start(inode, 1);
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if (!IS_ERR(handle))
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ext4_mark_inode_dirty(handle, inode);
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ret = ext4_mark_inode_dirty(handle, inode);
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return ret;
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}
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}
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ret = 0;
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}
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out:
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if (handle && !IS_ERR(handle))
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ext4_journal_stop(handle);
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return ret;
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}
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static int ext4_bh_unmapped_or_delay(handle_t *handle, struct buffer_head *bh)
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{
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return !buffer_mapped(bh) || buffer_delay(bh);
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}
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/* FIXME!! only support data=writeback mode */
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/*
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* get called vi ext4_da_writepages after taking page lock
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* We may end up doing block allocation here in case
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* mpage_da_map_blocks failed to allocate blocks.
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*/
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static int ext4_da_writepage(struct page *page,
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struct writeback_control *wbc)
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{
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struct inode *inode = page->mapping->host;
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handle_t *handle = NULL;
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int ret = 0;
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int err;
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loff_t size;
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unsigned long len;
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handle_t *handle = NULL;
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struct buffer_head *page_bufs;
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struct inode *inode = page->mapping->host;
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if (ext4_journal_current_handle())
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goto out_fail;
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handle = ext4_journal_current_handle();
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if (!handle) {
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/*
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* This can happen when we aren't called via
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* ext4_da_writepages() but directly (shrink_page_list).
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* We cannot easily start a transaction here so we just skip
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* writing the page in case we would have to do so.
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*/
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size = i_size_read(inode);
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handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
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if (IS_ERR(handle)) {
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ret = PTR_ERR(handle);
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goto out_fail;
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page_bufs = page_buffers(page);
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if (page->index == size >> PAGE_CACHE_SHIFT)
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len = size & ~PAGE_CACHE_MASK;
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else
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len = PAGE_CACHE_SIZE;
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if (walk_page_buffers(NULL, page_bufs, 0,
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len, NULL, ext4_bh_unmapped_or_delay)) {
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/*
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* We can't do block allocation under
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* page lock without a handle . So redirty
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* the page and return
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*/
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BUG_ON(wbc->sync_mode != WB_SYNC_NONE);
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redirty_page_for_writepage(wbc, page);
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unlock_page(page);
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return 0;
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}
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}
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if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
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ret = nobh_writepage(page, ext4_get_block, wbc);
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ret = nobh_writepage(page, ext4_da_get_block_write, wbc);
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else
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ret = block_write_full_page(page, ext4_get_block, wbc);
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ret = block_write_full_page(page, ext4_da_get_block_write, wbc);
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if (!ret && inode->i_size > EXT4_I(inode)->i_disksize) {
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EXT4_I(inode)->i_disksize = inode->i_size;
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ext4_mark_inode_dirty(handle, inode);
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}
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err = ext4_journal_stop(handle);
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if (!ret)
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ret = err;
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return ret;
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out_fail:
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redirty_page_for_writepage(wbc, page);
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unlock_page(page);
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return ret;
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}
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/*
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* For now just follow the DIO way to estimate the max credits
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* needed to write out EXT4_MAX_WRITEBACK_PAGES.
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* todo: need to calculate the max credits need for
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* extent based files, currently the DIO credits is based on
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* indirect-blocks mapping way.
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*
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* Probably should have a generic way to calculate credits
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* for DIO, writepages, and truncate
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*/
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#define EXT4_MAX_WRITEBACK_PAGES DIO_MAX_BLOCKS
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#define EXT4_MAX_WRITEBACK_CREDITS DIO_CREDITS
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static int ext4_da_writepages(struct address_space *mapping,
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struct writeback_control *wbc)
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{
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return mpage_da_writepages(mapping, wbc, ext4_da_get_block_write);
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struct inode *inode = mapping->host;
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handle_t *handle = NULL;
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int needed_blocks;
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int ret = 0;
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long to_write;
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loff_t range_start = 0;
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/*
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* No pages to write? This is mainly a kludge to avoid starting
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* a transaction for special inodes like journal inode on last iput()
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* because that could violate lock ordering on umount
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*/
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if (!mapping->nrpages)
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return 0;
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/*
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* Estimate the worse case needed credits to write out
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* EXT4_MAX_BUF_BLOCKS pages
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*/
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needed_blocks = EXT4_MAX_WRITEBACK_CREDITS;
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to_write = wbc->nr_to_write;
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if (!wbc->range_cyclic) {
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/*
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* If range_cyclic is not set force range_cont
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* and save the old writeback_index
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*/
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wbc->range_cont = 1;
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range_start = wbc->range_start;
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}
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while (!ret && to_write) {
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/* start a new transaction*/
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handle = ext4_journal_start(inode, needed_blocks);
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if (IS_ERR(handle)) {
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ret = PTR_ERR(handle);
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goto out_writepages;
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}
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/*
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* set the max dirty pages could be write at a time
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* to fit into the reserved transaction credits
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*/
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if (wbc->nr_to_write > EXT4_MAX_WRITEBACK_PAGES)
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wbc->nr_to_write = EXT4_MAX_WRITEBACK_PAGES;
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to_write -= wbc->nr_to_write;
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ret = mpage_da_writepages(mapping, wbc,
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ext4_da_get_block_write);
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ext4_journal_stop(handle);
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if (wbc->nr_to_write) {
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/*
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* There is no more writeout needed
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* or we requested for a noblocking writeout
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* and we found the device congested
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*/
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to_write += wbc->nr_to_write;
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break;
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}
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wbc->nr_to_write = to_write;
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}
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out_writepages:
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wbc->nr_to_write = to_write;
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if (range_start)
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wbc->range_start = range_start;
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return ret;
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}
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static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
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@ -2137,11 +2229,6 @@ out:
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return ret;
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}
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static int ext4_bh_unmapped_or_delay(handle_t *handle, struct buffer_head *bh)
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{
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return !buffer_mapped(bh) || buffer_delay(bh);
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}
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static int ext4_da_write_end(struct file *file,
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struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied,
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