gfs2: Implement fallocate(FALLOC_FL_PUNCH_HOLE)

Implement the top-level bits of punching a hole into a file.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

3 files changed, 134 insertions, 8 deletions

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index f6dbd2f400cc..2ec11981e694 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1351,7 +1351,7 @@ static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length)
         u64 lblock = (offset + (1 << bsize_shift) - 1) >> bsize_shift;
         __u16 start_list[GFS2_MAX_META_HEIGHT];
         __u16 __end_list[GFS2_MAX_META_HEIGHT], *end_list = NULL;
-        unsigned int start_aligned, end_aligned;
+        unsigned int start_aligned, uninitialized_var(end_aligned);
         unsigned int strip_h = ip->i_height - 1;
         u32 btotal = 0;
         int ret, state;
@@ -1956,3 +1956,123 @@ int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
         return 0;
 }
 
+static int stuffed_zero_range(struct inode *inode, loff_t offset, loff_t length)
+{
+        struct gfs2_inode *ip = GFS2_I(inode);
+        struct buffer_head *dibh;
+        int error;
+
+        if (offset >= inode->i_size)
+                return 0;
+        if (offset + length > inode->i_size)
+                length = inode->i_size - offset;
+
+        error = gfs2_meta_inode_buffer(ip, &dibh);
+        if (error)
+                return error;
+        gfs2_trans_add_meta(ip->i_gl, dibh);
+        memset(dibh->b_data + sizeof(struct gfs2_dinode) + offset, 0,
+               length);
+        brelse(dibh);
+        return 0;
+}
+
+static int gfs2_journaled_truncate_range(struct inode *inode, loff_t offset,
+                                         loff_t length)
+{
+        struct gfs2_sbd *sdp = GFS2_SB(inode);
+        loff_t max_chunk = GFS2_JTRUNC_REVOKES * sdp->sd_vfs->s_blocksize;
+        int error;
+
+        while (length) {
+                struct gfs2_trans *tr;
+                loff_t chunk;
+                unsigned int offs;
+
+                chunk = length;
+                if (chunk > max_chunk)
+                        chunk = max_chunk;
+
+                offs = offset & ~PAGE_MASK;
+                if (offs && chunk > PAGE_SIZE)
+                        chunk = offs + ((chunk - offs) & PAGE_MASK);
+
+                truncate_pagecache_range(inode, offset, chunk);
+                offset += chunk;
+                length -= chunk;
+
+                tr = current->journal_info;
+                if (!test_bit(TR_TOUCHED, &tr->tr_flags))
+                        continue;
+
+                gfs2_trans_end(sdp);
+                error = gfs2_trans_begin(sdp, RES_DINODE, GFS2_JTRUNC_REVOKES);
+                if (error)
+                        return error;
+        }
+        return 0;
+}
+
+int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
+{
+        struct inode *inode = file_inode(file);
+        struct gfs2_inode *ip = GFS2_I(inode);
+        struct gfs2_sbd *sdp = GFS2_SB(inode);
+        int error;
+
+        if (gfs2_is_jdata(ip))
+                error = gfs2_trans_begin(sdp, RES_DINODE + 2 * RES_JDATA,
+                                         GFS2_JTRUNC_REVOKES);
+        else
+                error = gfs2_trans_begin(sdp, RES_DINODE, 0);
+        if (error)
+                return error;
+
+        if (gfs2_is_stuffed(ip)) {
+                error = stuffed_zero_range(inode, offset, length);
+                if (error)
+                        goto out;
+        } else {
+                unsigned int start_off, end_off, blocksize;
+
+                blocksize = i_blocksize(inode);
+                start_off = offset & (blocksize - 1);
+                end_off = (offset + length) & (blocksize - 1);
+                if (start_off) {
+                        unsigned int len = length;
+                        if (length > blocksize - start_off)
+                                len = blocksize - start_off;
+                        error = gfs2_block_zero_range(inode, offset, len);
+                        if (error)
+                                goto out;
+                        if (start_off + length < blocksize)
+                                end_off = 0;
+                }
+                if (end_off) {
+                        error = gfs2_block_zero_range(inode,
+                                offset + length - end_off, end_off);
+                        if (error)
+                                goto out;
+                }
+        }
+
+        if (gfs2_is_jdata(ip)) {
+                BUG_ON(!current->journal_info);
+                gfs2_journaled_truncate_range(inode, offset, length);
+        } else
+                truncate_pagecache_range(inode, offset, offset + length - 1);
+
+        file_update_time(file);
+        mark_inode_dirty(inode);
+
+        if (current->journal_info)
+                gfs2_trans_end(sdp);
+
+        if (!gfs2_is_stuffed(ip))
+                error = punch_hole(ip, offset, length);
+
+out:
+        if (current->journal_info)
+                gfs2_trans_end(sdp);
+        return error;
+}
diff --git a/fs/gfs2/bmap.h b/fs/gfs2/bmap.h
index 443cc182cf18..c3402fe00653 100644
--- a/fs/gfs2/bmap.h
+++ b/fs/gfs2/bmap.h
@@ -61,5 +61,6 @@ extern int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
                                      unsigned int len);
 extern int gfs2_map_journal_extents(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd);
 extern void gfs2_free_journal_extents(struct gfs2_jdesc *jd);
+extern int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length);
 
 #endif /* __BMAP_DOT_H__ */
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 58705ef8643a..bd60dc682676 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -924,7 +924,7 @@ static long gfs2_fallocate(struct file *file, int mode, loff_t offset, loff_t le
         struct gfs2_holder gh;
         int ret;
 
-        if (mode & ~FALLOC_FL_KEEP_SIZE)
+        if (mode & ~(FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE))
                 return -EOPNOTSUPP;
         /* fallocate is needed by gfs2_grow to reserve space in the rindex */
         if (gfs2_is_jdata(ip) && inode != sdp->sd_rindex)
@@ -948,13 +948,18 @@ static long gfs2_fallocate(struct file *file, int mode, loff_t offset, loff_t le
         if (ret)
                 goto out_unlock;
 
-        ret = gfs2_rsqa_alloc(ip);
-        if (ret)
-                goto out_putw;
+        if (mode & FALLOC_FL_PUNCH_HOLE) {
+                ret = __gfs2_punch_hole(file, offset, len);
+        } else {
+                ret = gfs2_rsqa_alloc(ip);
+                if (ret)
+                        goto out_putw;
 
-        ret = __gfs2_fallocate(file, mode, offset, len);
-        if (ret)
-                gfs2_rs_deltree(&ip->i_res);
+                ret = __gfs2_fallocate(file, mode, offset, len);
+
+                if (ret)
+                        gfs2_rs_deltree(&ip->i_res);
+        }
 
 out_putw:
         put_write_access(inode);