[PATCH] ufs: fix hang during `rm'

This fixes the code like this:

	bh = sb_find_get_block (sb, tmp + j);
	if ((bh && DATA_BUFFER_USED(bh)) || tmp != fs32_to_cpu(sb, *p)) {
		retry = 1;
		brelse (bh);
		goto next1;
	}
	bforget (bh);

sb_find_get_block() ordinarily returns a buffer_head with b_count>=2, and
this code assume that in case if "b_count>1" buffer is used, so this caused
infinite loop.

(akpm: that is-the-buffer-busy code is incomprehensible.  Good riddance.  Use
of block_truncate_page() seems sane).

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 17 insertions, 57 deletions

diff --git a/fs/ufs/inode.c b/fs/ufs/inode.c
index e0c04e36a051..3c3f62ce2ad9 100644
--- a/fs/ufs/inode.c
+++ b/fs/ufs/inode.c
@@ -376,7 +376,7 @@ out:
  * This function gets the block which contains the fragment.
  */
 
-static int ufs_getfrag_block (struct inode *inode, sector_t fragment, struct buffer_head *bh_result, int create)
+int ufs_getfrag_block (struct inode *inode, sector_t fragment, struct buffer_head *bh_result, int create)
 {
         struct super_block * sb = inode->i_sb;
         struct ufs_sb_private_info * uspi = UFS_SB(sb)->s_uspi;
diff --git a/fs/ufs/truncate.c b/fs/ufs/truncate.c
index 61d2e35012a4..02e86291ef8a 100644
--- a/fs/ufs/truncate.c
+++ b/fs/ufs/truncate.c
@@ -29,6 +29,11 @@
  * Idea from Pierre del Perugia <delperug@gla.ecoledoc.ibp.fr>
  */
 
+/*
+ * Modified to avoid infinite loop on 2006 by
+ * Evgeniy Dushistov <dushistov@mail.ru>
+ */
+
 #include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/ufs_fs.h>
@@ -65,19 +70,16 @@
 #define DIRECT_BLOCK ((inode->i_size + uspi->s_bsize - 1) >> uspi->s_bshift)
 #define DIRECT_FRAGMENT ((inode->i_size + uspi->s_fsize - 1) >> uspi->s_fshift)
 
-#define DATA_BUFFER_USED(bh) \
-        (atomic_read(&bh->b_count)>1 || buffer_locked(bh))
 
 static int ufs_trunc_direct (struct inode * inode)
 {
         struct ufs_inode_info *ufsi = UFS_I(inode);
         struct super_block * sb;
         struct ufs_sb_private_info * uspi;
-        struct buffer_head * bh;
         __fs32 * p;
         unsigned frag1, frag2, frag3, frag4, block1, block2;
         unsigned frag_to_free, free_count;
-        unsigned i, j, tmp;
+        unsigned i, tmp;
         int retry;
         
         UFSD(("ENTER\n"))
@@ -117,15 +119,7 @@ static int ufs_trunc_direct (struct inode * inode)
                 ufs_panic (sb, "ufs_trunc_direct", "internal error");
         frag1 = ufs_fragnum (frag1);
         frag2 = ufs_fragnum (frag2);
-        for (j = frag1; j < frag2; j++) {
-                bh = sb_find_get_block (sb, tmp + j);
-                if ((bh && DATA_BUFFER_USED(bh)) || tmp != fs32_to_cpu(sb, *p)) {
-                        retry = 1;
-                        brelse (bh);
-                        goto next1;
-                }
-                bforget (bh);
-        }
+
         inode->i_blocks -= (frag2-frag1) << uspi->s_nspfshift;
         mark_inode_dirty(inode);
         ufs_free_fragments (inode, tmp + frag1, frag2 - frag1);
@@ -140,15 +134,7 @@ next1:
                 tmp = fs32_to_cpu(sb, *p);
                 if (!tmp)
                         continue;
-                for (j = 0; j < uspi->s_fpb; j++) {
-                        bh = sb_find_get_block(sb, tmp + j);
-                        if ((bh && DATA_BUFFER_USED(bh)) || tmp != fs32_to_cpu(sb, *p)) {
-                                retry = 1;
-                                brelse (bh);
-                                goto next2;
-                        }
-                        bforget (bh);
-                }
+
                 *p = 0;
                 inode->i_blocks -= uspi->s_nspb;
                 mark_inode_dirty(inode);
@@ -162,7 +148,6 @@ next1:
                         frag_to_free = tmp;
                         free_count = uspi->s_fpb;
                 }
-next2:;
         }
         
         if (free_count > 0)
@@ -179,15 +164,7 @@ next2:;
         if (!tmp )
                 ufs_panic(sb, "ufs_truncate_direct", "internal error");
         frag4 = ufs_fragnum (frag4);
-        for (j = 0; j < frag4; j++) {
-                bh = sb_find_get_block (sb, tmp + j);
-                if ((bh && DATA_BUFFER_USED(bh)) || tmp != fs32_to_cpu(sb, *p)) {
-                        retry = 1;
-                        brelse (bh);
-                        goto next1;
-                }
-                bforget (bh);
-        }
+
         *p = 0;
         inode->i_blocks -= frag4 << uspi->s_nspfshift;
         mark_inode_dirty(inode);
@@ -204,9 +181,8 @@ static int ufs_trunc_indirect (struct inode * inode, unsigned offset, __fs32 *p)
         struct super_block * sb;
         struct ufs_sb_private_info * uspi;
         struct ufs_buffer_head * ind_ubh;
-        struct buffer_head * bh;
         __fs32 * ind;
-        unsigned indirect_block, i, j, tmp;
+        unsigned indirect_block, i, tmp;
         unsigned frag_to_free, free_count;
         int retry;
 
@@ -238,15 +214,7 @@ static int ufs_trunc_indirect (struct inode * inode, unsigned offset, __fs32 *p)
                 tmp = fs32_to_cpu(sb, *ind);
                 if (!tmp)
                         continue;
-                for (j = 0; j < uspi->s_fpb; j++) {
-                        bh = sb_find_get_block(sb, tmp + j);
-                        if ((bh && DATA_BUFFER_USED(bh)) || tmp != fs32_to_cpu(sb, *ind)) {
-                                retry = 1;
-                                brelse (bh);
-                                goto next;
-                        }
-                        bforget (bh);
-                }       
+
                 *ind = 0;
                 ubh_mark_buffer_dirty(ind_ubh);
                 if (free_count == 0) {
@@ -261,7 +229,6 @@ static int ufs_trunc_indirect (struct inode * inode, unsigned offset, __fs32 *p)
                 }
                 inode->i_blocks -= uspi->s_nspb;
                 mark_inode_dirty(inode);
-next:;
         }
 
         if (free_count > 0) {
@@ -430,9 +397,7 @@ void ufs_truncate (struct inode * inode)
         struct ufs_inode_info *ufsi = UFS_I(inode);
         struct super_block * sb;
         struct ufs_sb_private_info * uspi;
-        struct buffer_head * bh;
-        unsigned offset;
-        int err, retry;
+        int retry;
         
         UFSD(("ENTER\n"))
         sb = inode->i_sb;
@@ -442,6 +407,9 @@ void ufs_truncate (struct inode * inode)
                 return;
         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
                 return;
+
+        block_truncate_page(inode->i_mapping,   inode->i_size, ufs_getfrag_block);
+
         lock_kernel();
         while (1) {
                 retry = ufs_trunc_direct(inode);
@@ -457,15 +425,7 @@ void ufs_truncate (struct inode * inode)
                 blk_run_address_space(inode->i_mapping);
                 yield();
         }
-        offset = inode->i_size & uspi->s_fshift;
-        if (offset) {
-                bh = ufs_bread (inode, inode->i_size >> uspi->s_fshift, 0, &err);
-                if (bh) {
-                        memset (bh->b_data + offset, 0, uspi->s_fsize - offset);
-                        mark_buffer_dirty (bh);
-                        brelse (bh);
-                }
-        }
+
         inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
         ufsi->i_lastfrag = DIRECT_FRAGMENT;
         unlock_kernel();