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Date: Sat, 12 Feb 2011 19:15:57 -0500
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH,RFC 7/7] ext4: move ext4_journal_start/stop to mpage_da_map_and_submit()
Previously, ext4_da_writepages() was responsible for calling
ext4_journal_start() and ext4_journal_stop(). If the blocks had
already been allocated (we don't support journal=data in
ext4_da_writepages), then there's no need to start a new journal
handle.
By moving ext4_journal_start/stop calls to mpage_da_map_and_submit()
we should significantly reduce the cpu usage (and cache line bouncing)
if the journal is enabled. This should (hopefully!) be especially
noticeable on large SMP systems.
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
fs/ext4/ext4.h | 3 +-
fs/ext4/inode.c | 125 ++++++++++++++++++++++++-------------------------------
2 files changed, 56 insertions(+), 72 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3aa0b72..be5c9e7 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -164,7 +164,8 @@ struct mpage_da_data {
unsigned long b_state; /* state of the extent */
unsigned long first_page, next_page; /* extent of pages */
struct writeback_control *wbc;
- int io_done;
+ int io_done:1;
+ int stop_writepages:1;
int pages_written;
int retval;
};
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 235a90e..ad1dc38 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2225,12 +2225,13 @@ static void ext4_print_free_blocks(struct inode *inode)
*/
static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
{
- int err, blks, get_blocks_flags;
+ int err, blks, get_blocks_flags, needed_blocks;
struct ext4_map_blocks map, *mapp = NULL;
sector_t next = mpd->b_blocknr;
unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
- handle_t *handle = NULL;
+ struct inode *inode = mpd->inode;
+ handle_t *handle;
/*
* If the blocks are mapped already, or we couldn't accumulate
@@ -2242,8 +2243,28 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
!(mpd->b_state & (1 << BH_Unwritten))))
goto submit_io;
- handle = ext4_journal_current_handle();
- BUG_ON(!handle);
+ /*
+ * Calculate the number of journal credits needed. In the
+ * non-extent case, the journal credits needed to insert
+ * nrblocks contiguous blocks is dependent on number of
+ * contiguous blocks. So we will limit this value to a sane
+ * value.
+ */
+ needed_blocks = EXT4_I(inode)->i_reserved_data_blocks;
+ if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
+ (needed_blocks > EXT4_MAX_TRANS_DATA))
+ needed_blocks = EXT4_MAX_TRANS_DATA;
+ needed_blocks = ext4_chunk_trans_blocks(inode, needed_blocks);
+
+ /* start a new transaction */
+ handle = ext4_journal_start(inode, needed_blocks);
+ if (IS_ERR(handle)) {
+ ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
+ "%ld pages, ino %lu; err %ld", __func__,
+ mpd->wbc->nr_to_write, inode->i_ino, PTR_ERR(handle));
+ mpd->stop_writepages = 1;
+ goto submit_io;
+ }
/*
* Call ext4_map_blocks() to allocate any delayed allocation
@@ -2266,15 +2287,16 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
map.m_lblk = next;
map.m_len = max_blocks;
get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
- if (ext4_should_dioread_nolock(mpd->inode))
+ if (ext4_should_dioread_nolock(inode))
get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
if (mpd->b_state & (1 << BH_Delay))
get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
- blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
+ blks = ext4_map_blocks(handle, inode, &map, get_blocks_flags);
if (blks < 0) {
- struct super_block *sb = mpd->inode->i_sb;
+ struct super_block *sb = inode->i_sb;
+ ext4_journal_stop(handle);
err = blks;
/*
* If get block returns EAGAIN or ENOSPC and there
@@ -2301,32 +2323,32 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
ext4_msg(sb, KERN_CRIT,
"delayed block allocation failed for inode %lu "
"at logical offset %llu with max blocks %zd "
- "with error %d", mpd->inode->i_ino,
+ "with error %d", inode->i_ino,
(unsigned long long) next,
- mpd->b_size >> mpd->inode->i_blkbits, err);
+ mpd->b_size >> inode->i_blkbits, err);
ext4_msg(sb, KERN_CRIT,
"This should not happen!! Data will be lost\n");
if (err == -ENOSPC)
- ext4_print_free_blocks(mpd->inode);
+ ext4_print_free_blocks(inode);
}
/* invalidate all the pages */
ext4_da_block_invalidatepages(mpd, next,
- mpd->b_size >> mpd->inode->i_blkbits);
+ mpd->b_size >> inode->i_blkbits);
return;
}
BUG_ON(blks == 0);
mapp = ↦
if (map.m_flags & EXT4_MAP_NEW) {
- struct block_device *bdev = mpd->inode->i_sb->s_bdev;
+ struct block_device *bdev = inode->i_sb->s_bdev;
int i;
for (i = 0; i < map.m_len; i++)
unmap_underlying_metadata(bdev, map.m_pblk + i);
}
- if (ext4_should_order_data(mpd->inode)) {
- err = ext4_jbd2_file_inode(handle, mpd->inode);
+ if (ext4_should_order_data(inode)) {
+ err = ext4_jbd2_file_inode(handle, inode);
if (err)
/* This only happens if the journal is aborted */
return;
@@ -2335,19 +2357,24 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
/*
* Update on-disk size along with block allocation.
*/
- disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
- if (disksize > i_size_read(mpd->inode))
- disksize = i_size_read(mpd->inode);
- if (disksize > EXT4_I(mpd->inode)->i_disksize) {
- ext4_update_i_disksize(mpd->inode, disksize);
- err = ext4_mark_inode_dirty(handle, mpd->inode);
+ disksize = ((loff_t) next + blks) << inode->i_blkbits;
+ if (disksize > i_size_read(inode))
+ disksize = i_size_read(inode);
+ if (disksize > EXT4_I(inode)->i_disksize) {
+ ext4_update_i_disksize(inode, disksize);
+ err = ext4_mark_inode_dirty(handle, inode);
if (err)
- ext4_error(mpd->inode->i_sb,
+ ext4_error(inode->i_sb,
"Failed to mark inode %lu dirty",
- mpd->inode->i_ino);
+ inode->i_ino);
}
+ ext4_journal_stop(handle);
submit_io:
+ /*
+ * This also doubles as the the way we unlock all of the pages
+ * in case of an error. Hacky, but it works...
+ */
mpage_da_submit_io(mpd, mapp);
mpd->io_done = 1;
}
@@ -2687,31 +2714,6 @@ static int ext4_writepage(struct page *page,
}
/*
- * 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.
- */
-
-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 (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
- (max_blocks > EXT4_MAX_TRANS_DATA))
- max_blocks = EXT4_MAX_TRANS_DATA;
-
- return ext4_chunk_trans_blocks(inode, max_blocks);
-}
-
-/*
* write_cache_pages_da - walk the list of dirty pages of the given
* address space and accumulate pages that need writing, and call
* mpage_da_map_and_submit to map a single contiguous memory region
@@ -2885,13 +2887,12 @@ static int ext4_da_writepages(struct address_space *mapping,
{
pgoff_t index;
int range_whole = 0;
- handle_t *handle = NULL;
struct mpage_da_data mpd;
struct inode *inode = mapping->host;
int pages_written = 0;
unsigned int max_pages;
int range_cyclic, cycled = 1, io_done = 0;
- int needed_blocks, ret = 0;
+ int ret = 0;
long desired_nr_to_write, nr_to_writebump = 0;
loff_t range_start = wbc->range_start;
struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
@@ -2899,6 +2900,7 @@ static int ext4_da_writepages(struct address_space *mapping,
pgoff_t end;
trace_ext4_da_writepages(inode, wbc);
+ BUG_ON(ext4_should_journal_data(inode));
/*
* No pages to write? This is mainly a kludge to avoid starting
@@ -2976,28 +2978,8 @@ retry:
tag_pages_for_writeback(mapping, index, end);
while (!ret && wbc->nr_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);
- ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
- "%ld pages, ino %lu; err %d", __func__,
- wbc->nr_to_write, inode->i_ino, ret);
- goto out_writepages;
- }
-
- /*
- * Now call write_cache_pages_da() to find the next
+ * Call write_cache_pages_da() to find the next
* contiguous region of logical blocks that need
* blocks to be allocated by ext4 and submit them.
*/
@@ -3014,7 +2996,8 @@ retry:
trace_ext4_da_write_pages(inode, &mpd);
wbc->nr_to_write -= mpd.pages_written;
- ext4_journal_stop(handle);
+ if (mpd.stop_writepages)
+ goto out_writepages;
if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
/* commit the transaction which would
--
1.7.3.1
--
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