[JFFS2] Prevent deadlock during write buffer recovery

Prevent deadlock when checking erased block for
space allocation during wbuf recovery.

Signed-off-by: Estelle Hammache <estelle.hammache@st.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 8 insertions, 4 deletions

diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index 4346940b487..79414abadd5 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -9,7 +9,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: wbuf.c,v 1.85 2005/02/02 22:12:04 dwmw2 Exp $
+ * $Id: wbuf.c,v 1.86 2005/02/05 18:23:37 hammache Exp $
  *
  */
 
@@ -865,7 +865,6 @@ int jffs2_flash_read(struct jffs2_sb_info *c, loff_t ofs, size_t len, size_t *re
 
         /* Read flash */
         if (!jffs2_can_mark_obsolete(c)) {
-                down_read(&c->wbuf_sem);
 
                 if (jffs2_cleanmarker_oob(c))
                         ret = c->mtd->read_ecc(c->mtd, ofs, len, retlen, buf, NULL, c->oobinfo);
@@ -892,11 +891,16 @@ int jffs2_flash_read(struct jffs2_sb_info *c, loff_t ofs, size_t len, size_t *re
 
         /* if no writebuffer available or write buffer empty, return */
         if (!c->wbuf_pagesize || !c->wbuf_len)
-                goto exit;
+                return ret;;
 
         /* if we read in a different block, return */
         if ( (ofs & ~(c->sector_size-1)) != (c->wbuf_ofs & ~(c->sector_size-1)) ) 
-                goto exit;
+                return ret;
+
+        /* Lock only if we have reason to believe wbuf contains relevant data,
+           so that checking an erased block during wbuf recovery space allocation
+           does not deadlock. */
+        down_read(&c->wbuf_sem);
 
         if (ofs >= c->wbuf_ofs) {
                 owbf = (ofs - c->wbuf_ofs);     /* offset in write buffer */