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Message-Id: <1369993379-13017-18-git-send-email-jack@suse.cz>
Date: Fri, 31 May 2013 11:42:50 +0200
From: Jan Kara <jack@...e.cz>
To: Ted Tso <tytso@....edu>
Cc: linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: [PATCH 17/26] ext4: Use transaction reservation for extent conversion in ext4_end_io
Later we would like to clear PageWriteback bit only after extent conversion
from unwritten to written extents is performed. However it is not possible
to start a transaction after PageWriteback is set because that violates
lock ordering (and is easy to deadlock). So we have to reserve a transaction
before locking pages and sending them for IO and later we use the transaction
for extent conversion from ext4_end_io().
Reviewed-by: Zheng Liu <wenqing.lz@...bao.com>
Signed-off-by: Jan Kara <jack@...e.cz>
---
fs/ext4/ext4.h | 12 +++++++++---
fs/ext4/ext4_jbd2.h | 5 +++--
fs/ext4/extents.c | 40 +++++++++++++++++++++++++++++-----------
fs/ext4/inode.c | 25 ++++++++++++++++++++-----
fs/ext4/page-io.c | 11 ++++++++---
5 files changed, 69 insertions(+), 24 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 406e447..ee436b9 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -184,10 +184,13 @@ struct ext4_map_blocks {
#define EXT4_IO_END_DIRECT 0x0004
/*
- * For converting uninitialized extents on a work queue.
+ * For converting uninitialized extents on a work queue. 'handle' is used for
+ * buffered writeback.
*/
typedef struct ext4_io_end {
struct list_head list; /* per-file finished IO list */
+ handle_t *handle; /* handle reserved for extent
+ * conversion */
struct inode *inode; /* file being written to */
unsigned int flag; /* unwritten or not */
loff_t offset; /* offset in the file */
@@ -1327,6 +1330,9 @@ static inline void ext4_set_io_unwritten_flag(struct inode *inode,
struct ext4_io_end *io_end)
{
if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
+ /* Writeback has to have coversion transaction reserved */
+ WARN_ON(EXT4_SB(inode->i_sb)->s_journal && !io_end->handle &&
+ !(io_end->flag & EXT4_IO_END_DIRECT));
io_end->flag |= EXT4_IO_END_UNWRITTEN;
atomic_inc(&EXT4_I(inode)->i_unwritten);
}
@@ -2593,8 +2599,8 @@ extern void ext4_ext_init(struct super_block *);
extern void ext4_ext_release(struct super_block *);
extern long ext4_fallocate(struct file *file, int mode, loff_t offset,
loff_t len);
-extern int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
- ssize_t len);
+extern int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
+ loff_t offset, ssize_t len);
extern int ext4_map_blocks(handle_t *handle, struct inode *inode,
struct ext4_map_blocks *map, int flags);
extern int ext4_ext_calc_metadata_amount(struct inode *inode,
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index fdd865e..2877258 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -134,7 +134,8 @@ static inline int ext4_jbd2_credits_xattr(struct inode *inode)
#define EXT4_HT_MIGRATE 8
#define EXT4_HT_MOVE_EXTENTS 9
#define EXT4_HT_XATTR 10
-#define EXT4_HT_MAX 11
+#define EXT4_HT_EXT_CONVERT 11
+#define EXT4_HT_MAX 12
/**
* struct ext4_journal_cb_entry - Base structure for callback information.
@@ -319,7 +320,7 @@ static inline handle_t *__ext4_journal_start(struct inode *inode,
#define ext4_journal_stop(handle) \
__ext4_journal_stop(__func__, __LINE__, (handle))
-#define ext4_journal_start_reserve(handle, type) \
+#define ext4_journal_start_reserved(handle, type) \
__ext4_journal_start_reserved((handle), __LINE__, (type))
handle_t *__ext4_journal_start_reserved(handle_t *handle, unsigned int line,
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e455141..f94f8b2 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4546,10 +4546,9 @@ retry:
* function, to convert the fallocated extents after IO is completed.
* Returns 0 on success.
*/
-int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
- ssize_t len)
+int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
+ loff_t offset, ssize_t len)
{
- handle_t *handle;
unsigned int max_blocks;
int ret = 0;
int ret2 = 0;
@@ -4564,16 +4563,32 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
max_blocks = ((EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits) -
map.m_lblk);
/*
- * credits to insert 1 extent into extent tree
+ * This is somewhat ugly but the idea is clear: When transaction is
+ * reserved, everything goes into it. Otherwise we rather start several
+ * smaller transactions for conversion of each extent separately.
*/
- credits = ext4_chunk_trans_blocks(inode, max_blocks);
+ if (handle) {
+ handle = ext4_journal_start_reserved(handle,
+ EXT4_HT_EXT_CONVERT);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+ credits = 0;
+ } else {
+ /*
+ * credits to insert 1 extent into extent tree
+ */
+ credits = ext4_chunk_trans_blocks(inode, max_blocks);
+ }
while (ret >= 0 && ret < max_blocks) {
map.m_lblk += ret;
map.m_len = (max_blocks -= ret);
- handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, credits);
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- break;
+ if (credits) {
+ handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
+ credits);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ break;
+ }
}
ret = ext4_map_blocks(handle, inode, &map,
EXT4_GET_BLOCKS_IO_CONVERT_EXT);
@@ -4584,10 +4599,13 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
inode->i_ino, map.m_lblk,
map.m_len, ret);
ext4_mark_inode_dirty(handle, inode);
- ret2 = ext4_journal_stop(handle);
- if (ret <= 0 || ret2 )
+ if (credits)
+ ret2 = ext4_journal_stop(handle);
+ if (ret <= 0 || ret2)
break;
}
+ if (!credits)
+ ret2 = ext4_journal_stop(handle);
return ret > 0 ? ret2 : ret;
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index de841d9..1f9a8f9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1406,6 +1406,7 @@ static void ext4_da_page_release_reservation(struct page *page,
struct mpage_da_data {
struct inode *inode;
struct writeback_control *wbc;
+
pgoff_t first_page; /* The first page to write */
pgoff_t next_page; /* Current page to examine */
pgoff_t last_page; /* Last page to examine */
@@ -2104,8 +2105,14 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
if (err < 0)
return err;
- if (map->m_flags & EXT4_MAP_UNINIT)
+ if (map->m_flags & EXT4_MAP_UNINIT) {
+ if (!mpd->io_submit.io_end->handle &&
+ ext4_handle_valid(handle)) {
+ mpd->io_submit.io_end->handle = handle->h_rsv_handle;
+ handle->h_rsv_handle = NULL;
+ }
ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
+ }
BUG_ON(map->m_len == 0);
if (map->m_flags & EXT4_MAP_NEW) {
@@ -2347,7 +2354,7 @@ static int ext4_da_writepages(struct address_space *mapping,
handle_t *handle = NULL;
struct mpage_da_data mpd;
struct inode *inode = mapping->host;
- int needed_blocks, ret = 0;
+ int needed_blocks, rsv_blocks = 0, ret = 0;
struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
bool done;
struct blk_plug plug;
@@ -2375,6 +2382,14 @@ static int ext4_da_writepages(struct address_space *mapping,
if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
return -EROFS;
+ if (ext4_should_dioread_nolock(inode)) {
+ /*
+ * We may need to convert upto one extent per block in
+ * the page and we may dirty the inode.
+ */
+ rsv_blocks = 1 + (PAGE_CACHE_SIZE >> inode->i_blkbits);
+ }
+
/*
* If we have inline data and arrive here, it means that
* we will soon create the block for the 1st page, so
@@ -2434,8 +2449,8 @@ retry:
needed_blocks = ext4_da_writepages_trans_blocks(inode);
/* start a new transaction */
- handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
- needed_blocks);
+ handle = ext4_journal_start_with_reserve(inode,
+ EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
@@ -3112,7 +3127,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
* for non AIO case, since the IO is already
* completed, we could do the conversion right here
*/
- err = ext4_convert_unwritten_extents(inode,
+ err = ext4_convert_unwritten_extents(NULL, inode,
offset, ret);
if (err < 0)
ret = err;
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index de6860c..5f20bc4 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -66,6 +66,7 @@ static void ext4_release_io_end(ext4_io_end_t *io_end)
{
BUG_ON(!list_empty(&io_end->list));
BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
+ WARN_ON(io_end->handle);
if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
wake_up_all(ext4_ioend_wq(io_end->inode));
@@ -92,13 +93,15 @@ static int ext4_end_io(ext4_io_end_t *io)
struct inode *inode = io->inode;
loff_t offset = io->offset;
ssize_t size = io->size;
+ handle_t *handle = io->handle;
int ret = 0;
ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
"list->prev 0x%p\n",
io, inode->i_ino, io->list.next, io->list.prev);
- ret = ext4_convert_unwritten_extents(inode, offset, size);
+ io->handle = NULL; /* Following call will use up the handle */
+ ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
if (ret < 0) {
ext4_msg(inode->i_sb, KERN_EMERG,
"failed to convert unwritten extents to written "
@@ -228,8 +231,10 @@ int ext4_put_io_end(ext4_io_end_t *io_end)
if (atomic_dec_and_test(&io_end->count)) {
if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
- err = ext4_convert_unwritten_extents(io_end->inode,
- io_end->offset, io_end->size);
+ err = ext4_convert_unwritten_extents(io_end->handle,
+ io_end->inode, io_end->offset,
+ io_end->size);
+ io_end->handle = NULL;
ext4_clear_io_unwritten_flag(io_end);
}
ext4_release_io_end(io_end);
--
1.8.1.4
--
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