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ext4: Retry block allocation if we have free blocks left
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When we truncate files, the meta-data blocks released are not reused
untill we commit the truncate transaction.  That means delayed get_block
request will return ENOSPC even if we have free blocks left.  Force a
journal commit and retry block allocation if we get ENOSPC with free
blocks left.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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Aneesh Kumar K.V authored and Theodore Ts'o committed Sep 9, 2008
1 parent 166348d commit df22291
Showing 1 changed file with 57 additions and 24 deletions.
81 changes: 57 additions & 24 deletions fs/ext4/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1634,6 +1634,7 @@ struct mpage_da_data {
struct writeback_control *wbc;
int io_done;
long pages_written;
int retval;
};

/*
Expand Down Expand Up @@ -1820,6 +1821,24 @@ static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
return;
}

static void ext4_print_free_blocks(struct inode *inode)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
printk(KERN_EMERG "Total free blocks count %lld\n",
ext4_count_free_blocks(inode->i_sb));
printk(KERN_EMERG "Free/Dirty block details\n");
printk(KERN_EMERG "free_blocks=%lld\n",
percpu_counter_sum(&sbi->s_freeblocks_counter));
printk(KERN_EMERG "dirty_blocks=%lld\n",
percpu_counter_sum(&sbi->s_dirtyblocks_counter));
printk(KERN_EMERG "Block reservation details\n");
printk(KERN_EMERG "i_reserved_data_blocks=%lu\n",
EXT4_I(inode)->i_reserved_data_blocks);
printk(KERN_EMERG "i_reserved_meta_blocks=%lu\n",
EXT4_I(inode)->i_reserved_meta_blocks);
return;
}

/*
* mpage_da_map_blocks - go through given space
*
Expand All @@ -1834,7 +1853,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
int err = 0;
struct buffer_head new;
struct buffer_head *lbh = &mpd->lbh;
sector_t next = lbh->b_blocknr;
sector_t next;

/*
* We consider only non-mapped and non-allocated blocks
Expand All @@ -1844,6 +1863,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
new.b_state = lbh->b_state;
new.b_blocknr = 0;
new.b_size = lbh->b_size;
next = lbh->b_blocknr;
/*
* If we didn't accumulate anything
* to write simply return
Expand All @@ -1860,6 +1880,13 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
*/
if (err == -EAGAIN)
return 0;

if (err == -ENOSPC &&
ext4_count_free_blocks(mpd->inode->i_sb)) {
mpd->retval = err;
return 0;
}

/*
* get block failure will cause us
* to loop in writepages. Because
Expand All @@ -1877,8 +1904,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
printk(KERN_EMERG "This should not happen.!! "
"Data will be lost\n");
if (err == -ENOSPC) {
printk(KERN_CRIT "Total free blocks count %lld\n",
ext4_count_free_blocks(mpd->inode->i_sb));
ext4_print_free_blocks(mpd->inode);
}
/* invlaidate all the pages */
ext4_da_block_invalidatepages(mpd, next,
Expand Down Expand Up @@ -2085,39 +2111,36 @@ static int __mpage_da_writepage(struct page *page,
*/
static int mpage_da_writepages(struct address_space *mapping,
struct writeback_control *wbc,
get_block_t get_block)
struct mpage_da_data *mpd)
{
struct mpage_da_data mpd;
long to_write;
int ret;

if (!get_block)
if (!mpd->get_block)
return generic_writepages(mapping, wbc);

mpd.wbc = wbc;
mpd.inode = mapping->host;
mpd.lbh.b_size = 0;
mpd.lbh.b_state = 0;
mpd.lbh.b_blocknr = 0;
mpd.first_page = 0;
mpd.next_page = 0;
mpd.get_block = get_block;
mpd.io_done = 0;
mpd.pages_written = 0;
mpd->lbh.b_size = 0;
mpd->lbh.b_state = 0;
mpd->lbh.b_blocknr = 0;
mpd->first_page = 0;
mpd->next_page = 0;
mpd->io_done = 0;
mpd->pages_written = 0;
mpd->retval = 0;

to_write = wbc->nr_to_write;

ret = write_cache_pages(mapping, wbc, __mpage_da_writepage, &mpd);
ret = write_cache_pages(mapping, wbc, __mpage_da_writepage, mpd);

/*
* Handle last extent of pages
*/
if (!mpd.io_done && mpd.next_page != mpd.first_page) {
if (mpage_da_map_blocks(&mpd) == 0)
mpage_da_submit_io(&mpd);
if (!mpd->io_done && mpd->next_page != mpd->first_page) {
if (mpage_da_map_blocks(mpd) == 0)
mpage_da_submit_io(mpd);
}

wbc->nr_to_write = to_write - mpd.pages_written;
wbc->nr_to_write = to_write - mpd->pages_written;
return ret;
}

Expand Down Expand Up @@ -2357,6 +2380,7 @@ static int ext4_da_writepages(struct address_space *mapping,
{
handle_t *handle = NULL;
loff_t range_start = 0;
struct mpage_da_data mpd;
struct inode *inode = mapping->host;
int needed_blocks, ret = 0, nr_to_writebump = 0;
long to_write, pages_skipped = 0;
Expand Down Expand Up @@ -2390,6 +2414,9 @@ static int ext4_da_writepages(struct address_space *mapping,
range_start = wbc->range_start;
pages_skipped = wbc->pages_skipped;

mpd.wbc = wbc;
mpd.inode = mapping->host;

restart_loop:
to_write = wbc->nr_to_write;
while (!ret && to_write > 0) {
Expand All @@ -2413,11 +2440,17 @@ static int ext4_da_writepages(struct address_space *mapping,
dump_stack();
goto out_writepages;
}

to_write -= wbc->nr_to_write;
ret = mpage_da_writepages(mapping, wbc,
ext4_da_get_block_write);

mpd.get_block = ext4_da_get_block_write;
ret = mpage_da_writepages(mapping, wbc, &mpd);

ext4_journal_stop(handle);

if (mpd.retval == -ENOSPC)
jbd2_journal_force_commit_nested(sbi->s_journal);

/* reset the retry count */
if (ret == MPAGE_DA_EXTENT_TAIL) {
/*
* got one extent now try with
Expand Down

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