[PATCH] UBIFS: pre-allocate bulk-read buffer

Artem Bityutskiy
2008-11-21T15:46:47Z

From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

To avoid memory allocation failure during bulk-read, pre-allocate
a bulk-read buffer, so that if there is only one bulk-reader at
a time, it would just use the pre-allocated buffer and would not
do any memory allocation. However, if there are more than 1 bulk-
reader, then only one reader would use the pre-allocated buffer,
while the other reader would allocate the buffer for itself.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
---
fs/ubifs/file.c | 31 ++++++++++++++++++++--------
fs/ubifs/super.c | 57 +++++++++++++++++++++++++++++++++++++++++++++--------
fs/ubifs/ubifs.h | 6 +++++
3 files changed, 76 insertions(+), 18 deletions(-)

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 0c5c27d..2624411 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -811,15 +811,15 @@ static int ubifs_bulk_read(struct page *page)
struct ubifs_inode *ui = ubifs_inode(inode);
pgoff_t index = page->index, last_page_read = ui->last_page_read;
struct bu_info *bu;
- int err = 0;
+ int err = 0, allocated = 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.
+ * Bulk-read is protected by @ui->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;
@@ -840,17 +840,30 @@ static int ubifs_bulk_read(struct page *page)
ui->bulk_read = 1;
}

- bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
- if (!bu)
- return 0;
+ /*
+ * If possible, try to use pre-allocated bulk-read information, which
+ * is protected by @c->bu_mutex.
+ */
+ if (mutex_trylock(&c->bu_mutex))
+ bu = &c->bu;
+ else {
+ bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
+ if (!bu)
+ goto out_unlock;
+
+ bu->buf = NULL;
+ allocated = 1;
+ }

- 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);
+
+ if (!allocated)
+ mutex_unlock(&c->bu_mutex);
+ else
+ kfree(bu);

out_unlock:
mutex_unlock(&ui->ui_mutex);
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 1d51156..d80b2ae 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -572,14 +572,6 @@ static int init_constants_early(struct ubifs_info *c)
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->max_bu_buf_len,
- GFP_KERNEL | __GFP_NOWARN);
- kfree(try);
- if (!try)
- c->max_bu_buf_len = UBIFS_KMALLOC_OK;
- }
return 0;
}

@@ -999,6 +991,34 @@ static void destroy_journal(struct ubifs_info *c)
}

/**
+ * bu_init - initialize bulk-read information.
+ * @c: UBIFS file-system description object
+ */
+static void bu_init(struct ubifs_info *c)
+{
+ ubifs_assert(c->bulk_read == 1);
+
+ if (c->bu.buf)
+ return; /* Already initialized */
+
+again:
+ c->bu.buf = kmalloc(c->max_bu_buf_len, GFP_KERNEL | __GFP_NOWARN);
+ if (!c->bu.buf) {
+ if (c->max_bu_buf_len > UBIFS_KMALLOC_OK) {
+ c->max_bu_buf_len = UBIFS_KMALLOC_OK;
+ goto again;
+ }
+
+ /* Just disable bulk-read */
+ ubifs_warn("Cannot allocate %d bytes of memory for bulk-read, "
+ "disabling it", c->max_bu_buf_len);
+ c->mount_opts.bulk_read = 1;
+ c->bulk_read = 0;
+ return;
+ }
+}
+
+/**
* mount_ubifs - mount UBIFS file-system.
* @c: UBIFS file-system description object
*
@@ -1066,6 +1086,13 @@ static int mount_ubifs(struct ubifs_info *c)
goto out_free;
}

+ if (c->bulk_read == 1)
+ bu_init(c);
+
+ /*
+ * We have to check all CRCs, even for data nodes, when we mount the FS
+ * (specifically, when we are replaying).
+ */
c->always_chk_crc = 1;

err = ubifs_read_superblock(c);
@@ -1296,6 +1323,7 @@ out_cbuf:
out_dereg:
dbg_failure_mode_deregistration(c);
out_free:
+ kfree(c->bu.buf);
vfree(c->ileb_buf);
vfree(c->sbuf);
kfree(c->bottom_up_buf);
@@ -1332,10 +1360,11 @@ static void ubifs_umount(struct ubifs_info *c)
kfree(c->cbuf);
kfree(c->rcvrd_mst_node);
kfree(c->mst_node);
+ kfree(c->bu.buf);
+ vfree(c->ileb_buf);
vfree(c->sbuf);
kfree(c->bottom_up_buf);
UBIFS_DBG(vfree(c->dbg_buf));
- vfree(c->ileb_buf);
dbg_failure_mode_deregistration(c);
}

@@ -1633,6 +1662,7 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
ubifs_err("invalid or unknown remount parameter");
return err;
}
+
if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
err = ubifs_remount_rw(c);
if (err)
@@ -1640,6 +1670,14 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
} else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY))
ubifs_remount_ro(c);

+ if (c->bulk_read == 1)
+ bu_init(c);
+ else {
+ dbg_gen("disable bulk-read");
+ kfree(c->bu.buf);
+ c->bu.buf = NULL;
+ }
+
return 0;
}

@@ -1730,6 +1768,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
mutex_init(&c->log_mutex);
mutex_init(&c->mst_mutex);
mutex_init(&c->umount_mutex);
+ mutex_init(&c->bu_mutex);
init_waitqueue_head(&c->cmt_wq);
c->buds = RB_ROOT;
c->old_idx = RB_ROOT;
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 870b5c4..46b1725 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -969,7 +969,10 @@ 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
+ *
* @max_bu_buf_len: maximum bulk-read buffer length
+ * @bu_mutex: protects the pre-allocated bulk-read buffer and @c->bu
+ * @bu: pre-allocated bulk-read information
*
* @log_lebs: number of logical eraseblocks in the log
* @log_bytes: log size in bytes
@@ -1217,7 +1220,10 @@ struct ubifs_info {
struct ubifs_mst_node *mst_node;
int mst_offs;
struct mutex mst_mutex;
+
int max_bu_buf_len;
+ struct mutex bu_mutex;
+ struct bu_info bu;

int log_lebs;
long long log_bytes;
--
1.5.4.3