GFS2: New truncate sequence

This updates GFS2's truncate code to use the new truncate
sequence correctly. This is a stepping stone to being
able to remove ip->i_disksize in favour of using i_size
everywhere now that the two sizes are always identical.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Christoph Hellwig <hch@lst.de>

1 files changed, 119 insertions, 128 deletions

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 6f482809d1a3..20b971ad4973 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -50,7 +50,7 @@ struct strip_mine {
  * @ip: the inode
  * @dibh: the dinode buffer
  * @block: the block number that was allocated
- * @private: any locked page held by the caller process
+ * @page: The (optional) page. This is looked up if @page is NULL
  *
  * Returns: errno
  */
@@ -109,8 +109,7 @@ static int gfs2_unstuffer_page(struct gfs2_inode *ip, struct buffer_head *dibh,
 /**
  * gfs2_unstuff_dinode - Unstuff a dinode when the data has grown too big
  * @ip: The GFS2 inode to unstuff
- * @unstuffer: the routine that handles unstuffing a non-zero length file
- * @private: private data for the unstuffer
+ * @page: The (optional) page. This is looked up if the @page is NULL
  *
  * This routine unstuffs a dinode and returns it to a "normal" state such
  * that the height can be grown in the traditional way.
@@ -885,83 +884,14 @@ out:
 }
 
 /**
- * do_grow - Make a file look bigger than it is
- * @ip: the inode
- * @size: the size to set the file to
- *
- * Called with an exclusive lock on @ip.
- *
- * Returns: errno
- */
-
-static int do_grow(struct gfs2_inode *ip, u64 size)
-{
-        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
-        struct gfs2_alloc *al;
-        struct buffer_head *dibh;
-        int error;
-
-        al = gfs2_alloc_get(ip);
-        if (!al)
-                return -ENOMEM;
-
-        error = gfs2_quota_lock_check(ip);
-        if (error)
-                goto out;
-
-        al->al_requested = sdp->sd_max_height + RES_DATA;
-
-        error = gfs2_inplace_reserve(ip);
-        if (error)
-                goto out_gunlock_q;
-
-        error = gfs2_trans_begin(sdp,
-                        sdp->sd_max_height + al->al_rgd->rd_length +
-                        RES_JDATA + RES_DINODE + RES_STATFS + RES_QUOTA, 0);
-        if (error)
-                goto out_ipres;
-
-        error = gfs2_meta_inode_buffer(ip, &dibh);
-        if (error)
-                goto out_end_trans;
-
-        if (size > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
-                if (gfs2_is_stuffed(ip)) {
-                        error = gfs2_unstuff_dinode(ip, NULL);
-                        if (error)
-                                goto out_brelse;
-                }
-        }
-
-        ip->i_disksize = size;
-        ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
-        gfs2_trans_add_bh(ip->i_gl, dibh, 1);
-        gfs2_dinode_out(ip, dibh->b_data);
-
-out_brelse:
-        brelse(dibh);
-out_end_trans:
-        gfs2_trans_end(sdp);
-out_ipres:
-        gfs2_inplace_release(ip);
-out_gunlock_q:
-        gfs2_quota_unlock(ip);
-out:
-        gfs2_alloc_put(ip);
-        return error;
-}
-
-
-/**
  * gfs2_block_truncate_page - Deal with zeroing out data for truncate
  *
  * This is partly borrowed from ext3.
  */
-static int gfs2_block_truncate_page(struct address_space *mapping)
+static int gfs2_block_truncate_page(struct address_space *mapping, loff_t from)
 {
         struct inode *inode = mapping->host;
         struct gfs2_inode *ip = GFS2_I(inode);
-        loff_t from = inode->i_size;
         unsigned long index = from >> PAGE_CACHE_SHIFT;
         unsigned offset = from & (PAGE_CACHE_SIZE-1);
         unsigned blocksize, iblock, length, pos;
@@ -1023,9 +953,11 @@ unlock:
         return err;
 }
 
-static int trunc_start(struct gfs2_inode *ip, u64 size)
+static int trunc_start(struct inode *inode, u64 oldsize, u64 newsize)
 {
-        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+        struct gfs2_inode *ip = GFS2_I(inode);
+        struct gfs2_sbd *sdp = GFS2_SB(inode);
+        struct address_space *mapping = inode->i_mapping;
         struct buffer_head *dibh;
         int journaled = gfs2_is_jdata(ip);
         int error;
@@ -1039,31 +971,27 @@ static int trunc_start(struct gfs2_inode *ip, u64 size)
         if (error)
                 goto out;
 
+        gfs2_trans_add_bh(ip->i_gl, dibh, 1);
+
         if (gfs2_is_stuffed(ip)) {
-                u64 dsize = size + sizeof(struct gfs2_dinode);
-                ip->i_disksize = size;
-                ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
-                gfs2_trans_add_bh(ip->i_gl, dibh, 1);
-                gfs2_dinode_out(ip, dibh->b_data);
-                if (dsize > dibh->b_size)
-                        dsize = dibh->b_size;
-                gfs2_buffer_clear_tail(dibh, dsize);
-                error = 1;
+                gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode) + newsize);
         } else {
-                if (size & (u64)(sdp->sd_sb.sb_bsize - 1))
-                        error = gfs2_block_truncate_page(ip->i_inode.i_mapping);
-
-                if (!error) {
-                        ip->i_disksize = size;
-                        ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
-                        ip->i_diskflags |= GFS2_DIF_TRUNC_IN_PROG;
-                        gfs2_trans_add_bh(ip->i_gl, dibh, 1);
-                        gfs2_dinode_out(ip, dibh->b_data);
+                if (newsize & (u64)(sdp->sd_sb.sb_bsize - 1)) {
+                        error = gfs2_block_truncate_page(mapping, newsize);
+                        if (error)
+                                goto out_brelse;
                 }
+                ip->i_diskflags |= GFS2_DIF_TRUNC_IN_PROG;
         }
 
-        brelse(dibh);
+        i_size_write(inode, newsize);
+        ip->i_disksize = newsize;
+        ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
+        gfs2_dinode_out(ip, dibh->b_data);
 
+        truncate_pagecache(inode, oldsize, newsize);
+out_brelse:
+        brelse(dibh);
 out:
         gfs2_trans_end(sdp);
         return error;
@@ -1143,86 +1071,149 @@ out:
 
 /**
  * do_shrink - make a file smaller
- * @ip: the inode
- * @size: the size to make the file
- * @truncator: function to truncate the last partial block
+ * @inode: the inode
+ * @oldsize: the current inode size
+ * @newsize: the size to make the file
  *
- * Called with an exclusive lock on @ip.
+ * Called with an exclusive lock on @inode. The @size must
+ * be equal to or smaller than the current inode size.
  *
  * Returns: errno
  */
 
-static int do_shrink(struct gfs2_inode *ip, u64 size)
+static int do_shrink(struct inode *inode, u64 oldsize, u64 newsize)
 {
+        struct gfs2_inode *ip = GFS2_I(inode);
         int error;
 
-        error = trunc_start(ip, size);
+        error = trunc_start(inode, oldsize, newsize);
         if (error < 0)
                 return error;
-        if (error > 0)
+        if (gfs2_is_stuffed(ip))
                 return 0;
 
-        error = trunc_dealloc(ip, size);
-        if (!error)
+        error = trunc_dealloc(ip, newsize);
+        if (error == 0)
                 error = trunc_end(ip);
 
         return error;
 }
 
-static int do_touch(struct gfs2_inode *ip, u64 size)
+void gfs2_trim_blocks(struct inode *inode)
 {
-        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+        u64 size = inode->i_size;
+        int ret;
+
+        ret = do_shrink(inode, size, size);
+        WARN_ON(ret != 0);
+}
+
+/**
+ * do_grow - Touch and update inode size
+ * @inode: The inode
+ * @size: The new size
+ *
+ * This function updates the timestamps on the inode and
+ * may also increase the size of the inode. This function
+ * must not be called with @size any smaller than the current
+ * inode size.
+ *
+ * Although it is not strictly required to unstuff files here,
+ * earlier versions of GFS2 have a bug in the stuffed file reading
+ * code which will result in a buffer overrun if the size is larger
+ * than the max stuffed file size. In order to prevent this from
+ * occuring, such files are unstuffed, but in other cases we can
+ * just update the inode size directly.
+ *
+ * Returns: 0 on success, or -ve on error
+ */
+
+static int do_grow(struct inode *inode, u64 size)
+{
+        struct gfs2_inode *ip = GFS2_I(inode);
+        struct gfs2_sbd *sdp = GFS2_SB(inode);
         struct buffer_head *dibh;
+        struct gfs2_alloc *al = NULL;
         int error;
 
-        error = gfs2_trans_begin(sdp, RES_DINODE, 0);
+        if (gfs2_is_stuffed(ip) &&
+            (size > (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)))) {
+                al = gfs2_alloc_get(ip);
+                if (al == NULL)
+                        return -ENOMEM;
+
+                error = gfs2_quota_lock_check(ip);
+                if (error)
+                        goto do_grow_alloc_put;
+
+                al->al_requested = 1;
+                error = gfs2_inplace_reserve(ip);
+                if (error)
+                        goto do_grow_qunlock;
+        }
+
+        error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
         if (error)
-                return error;
+                goto do_grow_release;
 
-        down_write(&ip->i_rw_mutex);
+        if (al) {
+                error = gfs2_unstuff_dinode(ip, NULL);
+                if (error)
+                        goto do_end_trans;
+        }
 
         error = gfs2_meta_inode_buffer(ip, &dibh);
         if (error)
-                goto do_touch_out;
+                goto do_end_trans;
 
+        i_size_write(inode, size);
+        ip->i_disksize = size;
         ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
         gfs2_dinode_out(ip, dibh->b_data);
         brelse(dibh);
 
-do_touch_out:
-        up_write(&ip->i_rw_mutex);
+do_end_trans:
         gfs2_trans_end(sdp);
+do_grow_release:
+        if (al) {
+                gfs2_inplace_release(ip);
+do_grow_qunlock:
+                gfs2_quota_unlock(ip);
+do_grow_alloc_put:
+                gfs2_alloc_put(ip);
+        }
         return error;
 }
 
 /**
- * gfs2_truncatei - make a file a given size
- * @ip: the inode
- * @size: the size to make the file
- * @truncator: function to truncate the last partial block
+ * gfs2_setattr_size - make a file a given size
+ * @inode: the inode
+ * @newsize: the size to make the file
  *
- * The file size can grow, shrink, or stay the same size.
+ * The file size can grow, shrink, or stay the same size. This
+ * is called holding i_mutex and an exclusive glock on the inode
+ * in question.
  *
  * Returns: errno
  */
 
-int gfs2_truncatei(struct gfs2_inode *ip, u64 size)
+int gfs2_setattr_size(struct inode *inode, u64 newsize)
 {
-        int error;
+        int ret;
+        u64 oldsize;
 
-        if (gfs2_assert_warn(GFS2_SB(&ip->i_inode), S_ISREG(ip->i_inode.i_mode)))
-                return -EINVAL;
+        BUG_ON(!S_ISREG(inode->i_mode));
 
-        if (size > ip->i_disksize)
-                error = do_grow(ip, size);
-        else if (size < ip->i_disksize)
-                error = do_shrink(ip, size);
-        else
-                /* update time stamps */
-                error = do_touch(ip, size);
+        ret = inode_newsize_ok(inode, newsize);
+        if (ret)
+                return ret;
 
-        return error;
+        oldsize = inode->i_size;
+        if (newsize >= oldsize)
+                return do_grow(inode, newsize);
+
+        return do_shrink(inode, oldsize, newsize);
 }
 
 int gfs2_truncatei_resume(struct gfs2_inode *ip)