提交 6c0c42cd 编写于 作者: A Artem Bityutskiy

UBIFS: do not allocate too much

Bulk-read allocates 128KiB or more using kmalloc. The allocation
starts failing often when the memory gets fragmented. UBIFS still
works fine in this case, because it falls-back to standard
(non-optimized) read method, though. This patch teaches bulk-read
to allocate exactly the amount of memory it needs, instead of
allocating 128KiB every time.

This patch is also a preparation to the further fix where we'll
have a pre-allocated bulk-read buffer as well. For example, now
the @bu object is prepared in 'ubifs_bulk_read()', so we could
path either pre-allocated or allocated information to
'ubifs_do_bulk_read()' later. Or teaching 'ubifs_do_bulk_read()'
not to allocate 'bu->buf' if it is already there.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
上级 39ce81ce
......@@ -691,32 +691,22 @@ static int populate_page(struct ubifs_info *c, struct page *page,
/**
* ubifs_do_bulk_read - do bulk-read.
* @c: UBIFS file-system description object
* @page1: first page
* @bu: bulk-read information
* @page1: first page to read
*
* This function returns %1 if the bulk-read is done, otherwise %0 is returned.
*/
static int ubifs_do_bulk_read(struct ubifs_info *c, struct page *page1)
static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu,
struct page *page1)
{
pgoff_t offset = page1->index, end_index;
struct address_space *mapping = page1->mapping;
struct inode *inode = mapping->host;
struct ubifs_inode *ui = ubifs_inode(inode);
struct bu_info *bu;
int err, page_idx, page_cnt, ret = 0, n = 0;
int allocate = bu->buf ? 0 : 1;
loff_t isize;
bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
if (!bu)
return 0;
bu->buf_len = c->bulk_read_buf_size;
bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN);
if (!bu->buf)
goto out_free;
data_key_init(c, &bu->key, inode->i_ino,
offset << UBIFS_BLOCKS_PER_PAGE_SHIFT);
err = ubifs_tnc_get_bu_keys(c, bu);
if (err)
goto out_warn;
......@@ -735,12 +725,25 @@ static int ubifs_do_bulk_read(struct ubifs_info *c, struct page *page1)
* together. If all the pages were like this, bulk-read would
* reduce performance, so we turn it off for a while.
*/
ui->read_in_a_row = 0;
ui->bulk_read = 0;
goto out_free;
goto out_bu_off;
}
if (bu->cnt) {
if (allocate) {
/*
* Allocate bulk-read buffer depending on how many data
* nodes we are going to read.
*/
bu->buf_len = bu->zbranch[bu->cnt - 1].offs +
bu->zbranch[bu->cnt - 1].len -
bu->zbranch[0].offs;
ubifs_assert(bu->buf_len > 0);
ubifs_assert(bu->buf_len <= c->leb_size);
bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN);
if (!bu->buf)
goto out_bu_off;
}
err = ubifs_tnc_bulk_read(c, bu);
if (err)
goto out_warn;
......@@ -779,13 +782,17 @@ static int ubifs_do_bulk_read(struct ubifs_info *c, struct page *page1)
ui->last_page_read = offset + page_idx - 1;
out_free:
kfree(bu->buf);
kfree(bu);
if (allocate)
kfree(bu->buf);
return ret;
out_warn:
ubifs_warn("ignoring error %d and skipping bulk-read", err);
goto out_free;
out_bu_off:
ui->read_in_a_row = ui->bulk_read = 0;
goto out_free;
}
/**
......@@ -803,18 +810,20 @@ static int ubifs_bulk_read(struct page *page)
struct ubifs_info *c = inode->i_sb->s_fs_info;
struct ubifs_inode *ui = ubifs_inode(inode);
pgoff_t index = page->index, last_page_read = ui->last_page_read;
int ret = 0;
struct bu_info *bu;
int err = 0;
ui->last_page_read = index;
if (!c->bulk_read)
return 0;
/*
* Bulk-read is protected by ui_mutex, but it is an optimization, so
* don't bother if we cannot lock the mutex.
*/
if (!mutex_trylock(&ui->ui_mutex))
return 0;
if (index != last_page_read + 1) {
/* Turn off bulk-read if we stop reading sequentially */
ui->read_in_a_row = 1;
......@@ -822,6 +831,7 @@ static int ubifs_bulk_read(struct page *page)
ui->bulk_read = 0;
goto out_unlock;
}
if (!ui->bulk_read) {
ui->read_in_a_row += 1;
if (ui->read_in_a_row < 3)
......@@ -829,10 +839,22 @@ static int ubifs_bulk_read(struct page *page)
/* Three reads in a row, so switch on bulk-read */
ui->bulk_read = 1;
}
ret = ubifs_do_bulk_read(c, page);
bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
if (!bu)
return 0;
bu->buf = NULL;
bu->buf_len = c->max_bu_buf_len;
data_key_init(c, &bu->key, inode->i_ino,
page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT);
err = ubifs_do_bulk_read(c, bu, page);
kfree(bu);
out_unlock:
mutex_unlock(&ui->ui_mutex);
return ret;
return err;
}
static int ubifs_readpage(struct file *file, struct page *page)
......
......@@ -569,16 +569,16 @@ static int init_constants_early(struct ubifs_info *c)
c->leb_overhead = c->leb_size % UBIFS_MAX_DATA_NODE_SZ;
/* Buffer size for bulk-reads */
c->bulk_read_buf_size = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
if (c->bulk_read_buf_size > c->leb_size)
c->bulk_read_buf_size = c->leb_size;
if (c->bulk_read_buf_size > UBIFS_KMALLOC_OK) {
c->max_bu_buf_len = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
if (c->max_bu_buf_len > c->leb_size)
c->max_bu_buf_len = c->leb_size;
if (c->max_bu_buf_len > UBIFS_KMALLOC_OK) {
/* Check if we can kmalloc that much */
void *try = kmalloc(c->bulk_read_buf_size,
void *try = kmalloc(c->max_bu_buf_len,
GFP_KERNEL | __GFP_NOWARN);
kfree(try);
if (!try)
c->bulk_read_buf_size = UBIFS_KMALLOC_OK;
c->max_bu_buf_len = UBIFS_KMALLOC_OK;
}
return 0;
}
......
......@@ -1501,7 +1501,12 @@ int ubifs_tnc_locate(struct ubifs_info *c, const union ubifs_key *key,
* @bu: bulk-read parameters and results
*
* Lookup consecutive data node keys for the same inode that reside
* consecutively in the same LEB.
* consecutively in the same LEB. This function returns zero in case of success
* and a negative error code in case of failure.
*
* Note, if the bulk-read buffer length (@bu->buf_len) is known, this function
* makes sure bulk-read nodes fit the buffer. Otherwise, this function prepares
* maxumum possible amount of nodes for bulk-read.
*/
int ubifs_tnc_get_bu_keys(struct ubifs_info *c, struct bu_info *bu)
{
......
......@@ -969,7 +969,7 @@ struct ubifs_mount_opts {
* @mst_node: master node
* @mst_offs: offset of valid master node
* @mst_mutex: protects the master node area, @mst_node, and @mst_offs
* @bulk_read_buf_size: buffer size for bulk-reads
* @max_bu_buf_len: maximum bulk-read buffer length
*
* @log_lebs: number of logical eraseblocks in the log
* @log_bytes: log size in bytes
......@@ -1217,7 +1217,7 @@ struct ubifs_info {
struct ubifs_mst_node *mst_node;
int mst_offs;
struct mutex mst_mutex;
int bulk_read_buf_size;
int max_bu_buf_len;
int log_lebs;
long long log_bytes;
......
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