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Subject[PATCH] ufs: change block number on the fly
This patch should fix current implementation of
"changing block numbers" to avoid kernel hangup,
data corruption and so on.

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>

---

diff -upr -X linux-2.6.17-rc4/Documentation/dontdiff linux-2.6.17-rc4-vanilla/fs/ufs/balloc.c linux-2.6.17-rc4/fs/ufs/balloc.c
--- linux-2.6.17-rc4-vanilla/fs/ufs/balloc.c 2006-05-17 11:46:45.147277000 +0400
+++ linux-2.6.17-rc4/fs/ufs/balloc.c 2006-05-17 10:14:55.554375500 +0400
@@ -39,7 +39,8 @@ static void ufs_clusteracct(struct super
/*
* Free 'count' fragments from fragment number 'fragment'
*/
-void ufs_free_fragments (struct inode * inode, unsigned fragment, unsigned count) {
+void ufs_free_fragments (struct inode * inode, unsigned fragment, unsigned count)
+{
struct super_block * sb;
struct ufs_sb_private_info * uspi;
struct ufs_super_block_first * usb1;
@@ -134,7 +135,8 @@ failed:
/*
* Free 'count' fragments from fragment number 'fragment' (free whole blocks)
*/
-void ufs_free_blocks (struct inode * inode, unsigned fragment, unsigned count) {
+void ufs_free_blocks (struct inode * inode, unsigned fragment, unsigned count)
+{
struct super_block * sb;
struct ufs_sb_private_info * uspi;
struct ufs_super_block_first * usb1;
@@ -222,15 +224,115 @@ failed:
return;
}

+static struct page * ufs_get_locked_page(struct address_space *mapping,
+ unsigned long index)
+{
+ struct page *page;
+try_again:
+ page = find_lock_page(mapping, index);
+ if (!page) {
+ page = read_cache_page(mapping, index,
+ (filler_t*)mapping->a_ops->readpage,
+ NULL);
+ if (IS_ERR(page)) {
+ printk(KERN_ERR "ufs_change_blocknr: "
+ "read_cache_page error: ino %lu, index: %lu\n",
+ mapping->host->i_ino, index);
+ goto out;
+ }
+
+ lock_page(page);
+
+ if (!PageUptodate(page) || PageError(page)) {
+ unlock_page(page);
+ page_cache_release(page);
+
+ printk(KERN_ERR "ufs_change_blocknr: "
+ "can not read page: ino %lu, index: %lu\n",
+ mapping->host->i_ino, index);
+
+ page = ERR_PTR(-EIO);
+ goto out;
+ }
+ }
+
+ if (unlikely(!page_has_buffers(page))) {
+ unlock_page(page);
+ page_cache_release(page);
+ goto try_again;/*we really need these buffers*/
+ }
+out:
+ return page;
+}
+
+/*
+ * Modify inode page cache in such way:
+ * have - blocks with b_blocknr equal to oldb...oldb+count-1
+ * get - blocks with b_blocknr equal to newb...newb+count-1
+ * also we suppose that oldb...oldb+count-1 blocks
+ * situated at the end of file.
+ *
+ * We can come here from ufs_writepage or ufs_prepare_write,
+ * locked_page is argument of these functions, so we already lock it.
+ */
+static void ufs_change_blocknr(struct inode *inode, unsigned int count,
+ unsigned int oldb, unsigned int newb,
+ struct page *locked_page)
+{
+ unsigned int blk_per_page = 1UL << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+ sector_t baseblk = ((inode->i_size-1)>>inode->i_blkbits) + 1 - count;
+ struct address_space *mapping = inode->i_mapping;
+ pgoff_t index, cur_index = locked_page->index;
+ unsigned int i, j;
+ struct page *page;
+ struct buffer_head *head, *bh;
+
+ UFSD(("ENTER, ino %lu, count %u, oldb %u, newb %u\n",
+ inode->i_ino, count, oldb, newb));
+
+ BUG_ON(!PageLocked(locked_page));
+
+ for (i = 0; i < count; i += blk_per_page) {
+ index = (baseblk+i) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+ if (likely(cur_index != index)) {
+ page = ufs_get_locked_page(mapping, index);
+ if (IS_ERR(page))
+ continue;
+ } else
+ page = locked_page;
+
+ j = i;
+ head = page_buffers(page);
+ bh = head;
+ do {
+ if (likely(bh->b_blocknr == j + oldb && j < count)) {
+ unmap_underlying_metadata(bh->b_bdev,
+ bh->b_blocknr);
+ bh->b_blocknr = newb + j++;
+ mark_buffer_dirty(bh);
+ }
+
+ bh = bh->b_this_page;
+ } while (bh != head);
+
+ set_page_dirty(page);
+
+ if (likely(cur_index != index)) {
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ }
+ UFSD(("EXIT\n"));
+}

-unsigned ufs_new_fragments (struct inode * inode, __fs32 * p, unsigned fragment,
- unsigned goal, unsigned count, int * err )
+unsigned ufs_new_fragments(struct inode * inode, __fs32 * p, unsigned fragment,
+ unsigned goal, unsigned count, int * err, struct page *locked_page)
{
struct super_block * sb;
struct ufs_sb_private_info * uspi;
struct ufs_super_block_first * usb1;
- struct buffer_head * bh;
- unsigned cgno, oldcount, newcount, tmp, request, i, result;
+ unsigned cgno, oldcount, newcount, tmp, request, result;

UFSD(("ENTER, ino %lu, fragment %u, goal %u, count %u\n", inode->i_ino, fragment, goal, count))

@@ -343,24 +445,8 @@ unsigned ufs_new_fragments (struct inode
}
result = ufs_alloc_fragments (inode, cgno, goal, request, err);
if (result) {
- for (i = 0; i < oldcount; i++) {
- bh = sb_bread(sb, tmp + i);
- if(bh)
- {
- clear_buffer_dirty(bh);
- bh->b_blocknr = result + i;
- mark_buffer_dirty (bh);
- if (IS_SYNC(inode))
- sync_dirty_buffer(bh);
- brelse (bh);
- }
- else
- {
- printk(KERN_ERR "ufs_new_fragments: bread fail\n");
- unlock_super(sb);
- return 0;
- }
- }
+ ufs_change_blocknr(inode, oldcount, tmp, result, locked_page);
+
*p = cpu_to_fs32(sb, result);
*err = 0;
inode->i_blocks += count << uspi->s_nspfshift;
diff -upr -X linux-2.6.17-rc4/Documentation/dontdiff linux-2.6.17-rc4-vanilla/fs/ufs/inode.c linux-2.6.17-rc4/fs/ufs/inode.c
--- linux-2.6.17-rc4-vanilla/fs/ufs/inode.c 2006-05-17 11:46:45.167278250 +0400
+++ linux-2.6.17-rc4/fs/ufs/inode.c 2006-05-16 13:36:27.447118250 +0400
@@ -173,9 +173,10 @@ static inline void ufs_clear_block(struc
}


-static struct buffer_head * ufs_inode_getfrag (struct inode *inode,
- unsigned int fragment, unsigned int new_fragment,
- unsigned int required, int *err, int metadata, long *phys, int *new)
+static struct buffer_head *ufs_inode_getfrag(struct inode *inode,
+ unsigned int fragment, unsigned int new_fragment,
+ unsigned int required, int *err, int metadata,
+ long *phys, int *new, struct page *locked_page)
{
struct ufs_inode_info *ufsi = UFS_I(inode);
struct super_block * sb;
@@ -233,7 +234,8 @@ repeat:
if (lastblockoff) {
p2 = ufsi->i_u1.i_data + lastblock;
tmp = ufs_new_fragments (inode, p2, lastfrag,
- fs32_to_cpu(sb, *p2), uspi->s_fpb - lastblockoff, err);
+ fs32_to_cpu(sb, *p2), uspi->s_fpb - lastblockoff,
+ err, locked_page);
if (!tmp) {
if (lastfrag != ufsi->i_lastfrag)
goto repeat;
@@ -245,14 +247,16 @@ repeat:
}
goal = fs32_to_cpu(sb, ufsi->i_u1.i_data[lastblock]) + uspi->s_fpb;
tmp = ufs_new_fragments (inode, p, fragment - blockoff,
- goal, required + blockoff, err);
+ goal, required + blockoff,
+ err, locked_page);
}
/*
* We will extend last allocated block
*/
else if (lastblock == block) {
- tmp = ufs_new_fragments (inode, p, fragment - (blockoff - lastblockoff),
- fs32_to_cpu(sb, *p), required + (blockoff - lastblockoff), err);
+ tmp = ufs_new_fragments(inode, p, fragment - (blockoff - lastblockoff),
+ fs32_to_cpu(sb, *p), required + (blockoff - lastblockoff),
+ err, locked_page);
}
/*
* We will allocate new block before last allocated block
@@ -260,8 +264,8 @@ repeat:
else /* (lastblock > block) */ {
if (lastblock && (tmp = fs32_to_cpu(sb, ufsi->i_u1.i_data[lastblock-1])))
goal = tmp + uspi->s_fpb;
- tmp = ufs_new_fragments (inode, p, fragment - blockoff,
- goal, uspi->s_fpb, err);
+ tmp = ufs_new_fragments(inode, p, fragment - blockoff,
+ goal, uspi->s_fpb, err, locked_page);
}
if (!tmp) {
if ((!blockoff && *p) ||
@@ -304,9 +308,10 @@ repeat2:
*/
}

-static struct buffer_head * ufs_block_getfrag (struct inode *inode,
- struct buffer_head *bh, unsigned int fragment, unsigned int new_fragment,
- unsigned int blocksize, int * err, int metadata, long *phys, int *new)
+static struct buffer_head *ufs_block_getfrag(struct inode *inode, struct buffer_head *bh,
+ unsigned int fragment, unsigned int new_fragment,
+ unsigned int blocksize, int * err, int metadata,
+ long *phys, int *new, struct page *locked_page)
{
struct super_block * sb;
struct ufs_sb_private_info * uspi;
@@ -351,7 +356,8 @@ repeat:
goal = tmp + uspi->s_fpb;
else
goal = bh->b_blocknr + uspi->s_fpb;
- tmp = ufs_new_fragments (inode, p, ufs_blknum(new_fragment), goal, uspi->s_fpb, err);
+ tmp = ufs_new_fragments(inode, p, ufs_blknum(new_fragment), goal,
+ uspi->s_fpb, err, locked_page);
if (!tmp) {
if (fs32_to_cpu(sb, *p))
goto repeat;
@@ -425,15 +431,15 @@ int ufs_getfrag_block (struct inode *ino
* it much more readable:
*/
#define GET_INODE_DATABLOCK(x) \
- ufs_inode_getfrag(inode, x, fragment, 1, &err, 0, &phys, &new)
+ ufs_inode_getfrag(inode, x, fragment, 1, &err, 0, &phys, &new, bh_result->b_page)
#define GET_INODE_PTR(x) \
- ufs_inode_getfrag(inode, x, fragment, uspi->s_fpb, &err, 1, NULL, NULL)
+ ufs_inode_getfrag(inode, x, fragment, uspi->s_fpb, &err, 1, NULL, NULL, bh_result->b_page)
#define GET_INDIRECT_DATABLOCK(x) \
- ufs_block_getfrag(inode, bh, x, fragment, sb->s_blocksize, \
- &err, 0, &phys, &new);
+ ufs_block_getfrag(inode, bh, x, fragment, sb->s_blocksize, \
+ &err, 0, &phys, &new, bh_result->b_page);
#define GET_INDIRECT_PTR(x) \
- ufs_block_getfrag(inode, bh, x, fragment, sb->s_blocksize, \
- &err, 1, NULL, NULL);
+ ufs_block_getfrag(inode, bh, x, fragment, sb->s_blocksize, \
+ &err, 1, NULL, NULL, bh_result->b_page);

if (ptr < UFS_NDIR_FRAGMENT) {
bh = GET_INODE_DATABLOCK(ptr);
diff -upr -X linux-2.6.17-rc4/Documentation/dontdiff linux-2.6.17-rc4-vanilla/include/linux/ufs_fs.h linux-2.6.17-rc4/include/linux/ufs_fs.h
--- linux-2.6.17-rc4-vanilla/include/linux/ufs_fs.h 2006-05-17 11:35:17.868324750 +0400
+++ linux-2.6.17-rc4/include/linux/ufs_fs.h 2006-05-16 13:36:27.447118250 +0400
@@ -876,7 +876,8 @@ struct ufs_super_block_third {
/* balloc.c */
extern void ufs_free_fragments (struct inode *, unsigned, unsigned);
extern void ufs_free_blocks (struct inode *, unsigned, unsigned);
-extern unsigned ufs_new_fragments (struct inode *, __fs32 *, unsigned, unsigned, unsigned, int *);
+extern unsigned ufs_new_fragments(struct inode *, __fs32 *, unsigned, unsigned,
+ unsigned, int *, struct page *);

/* cylinder.c */
extern struct ufs_cg_private_info * ufs_load_cylinder (struct super_block *, unsigned);
--
/Evgeniy

-
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