gfs2: gfs2_iomap_begin cleanup

Following commit d0a22a4b03b8 ("gfs2: Fix iomap write page reclaim deadlock"),
gfs2_iomap_begin and gfs2_iomap_begin_write can be further cleaned up and the
split between those two functions can be improved.

With suggestions from Christoph Hellwig.

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

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 4f8b5fd..907b794 100644 (file)
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1065,54 +1065,38 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 {
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
-       unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
-       bool unstuff, alloc_required;
+       bool unstuff;
        int ret;
 
-       ret = gfs2_write_lock(inode);
-       if (ret)
-               return ret;
-
        unstuff = gfs2_is_stuffed(ip) &&
                  pos + length > gfs2_max_stuffed_size(ip);
 
-       ret = gfs2_iomap_get(inode, pos, length, flags, iomap, mp);
-       if (ret)
-               goto out_unlock;
-
-       alloc_required = unstuff || iomap->type == IOMAP_HOLE;
+       if (unstuff || iomap->type == IOMAP_HOLE) {
+               unsigned int data_blocks, ind_blocks;
+               struct gfs2_alloc_parms ap = {};
+               unsigned int rblocks;
+               struct gfs2_trans *tr;
 
-       if (alloc_required || gfs2_is_jdata(ip))
                gfs2_write_calc_reserv(ip, iomap->length, &data_blocks,
                                       &ind_blocks);
-
-       if (alloc_required) {
-               struct gfs2_alloc_parms ap = {
-                       .target = data_blocks + ind_blocks
-               };
-
+               ap.target = data_blocks + ind_blocks;
                ret = gfs2_quota_lock_check(ip, &ap);
                if (ret)
-                       goto out_unlock;
+                       return ret;
 
                ret = gfs2_inplace_reserve(ip, &ap);
                if (ret)
                        goto out_qunlock;
-       }
 
-       rblocks = RES_DINODE + ind_blocks;
-       if (gfs2_is_jdata(ip))
-               rblocks += data_blocks;
-       if (ind_blocks || data_blocks)
-               rblocks += RES_STATFS + RES_QUOTA;
-       if (inode == sdp->sd_rindex)
-               rblocks += 2 * RES_STATFS;
-       if (alloc_required)
+               rblocks = RES_DINODE + ind_blocks;
+               if (gfs2_is_jdata(ip))
+                       rblocks += data_blocks;
+               if (ind_blocks || data_blocks)
+                       rblocks += RES_STATFS + RES_QUOTA;
+               if (inode == sdp->sd_rindex)
+                       rblocks += 2 * RES_STATFS;
                rblocks += gfs2_rg_blocks(ip, data_blocks + ind_blocks);
 
-       if (unstuff || iomap->type == IOMAP_HOLE) {
-               struct gfs2_trans *tr;
-
                ret = gfs2_trans_begin(sdp, rblocks,
                                       iomap->length >> inode->i_blkbits);
                if (ret)
@@ -1153,16 +1137,17 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 out_trans_end:
        gfs2_trans_end(sdp);
 out_trans_fail:
-       if (alloc_required)
-               gfs2_inplace_release(ip);
+       gfs2_inplace_release(ip);
 out_qunlock:
-       if (alloc_required)
-               gfs2_quota_unlock(ip);
-out_unlock:
-       gfs2_write_unlock(inode);
+       gfs2_quota_unlock(ip);
        return ret;
 }
 
+static inline bool gfs2_iomap_need_write_lock(unsigned flags)
+{
+       return (flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT);
+}
+
 static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
                            unsigned flags, struct iomap *iomap)
 {
@@ -1173,20 +1158,39 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
        iomap->flags |= IOMAP_F_BUFFER_HEAD;
 
        trace_gfs2_iomap_start(ip, pos, length, flags);
-       if ((flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT)) {
-               ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap, &mp);
-       } else {
-               ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
+       if (gfs2_iomap_need_write_lock(flags)) {
+               ret = gfs2_write_lock(inode);
+               if (ret)
+                       goto out;
+       }
 
-               /*
-                * Silently fall back to buffered I/O for stuffed files or if
-                * we've hot a hole (see gfs2_file_direct_write).
-                */
-               if ((flags & IOMAP_WRITE) && (flags & IOMAP_DIRECT) &&
-                   iomap->type != IOMAP_MAPPED)
-                       ret = -ENOTBLK;
+       ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
+       if (ret)
+               goto out_unlock;
+
+       switch(flags & IOMAP_WRITE) {
+       case IOMAP_WRITE:
+               if (flags & IOMAP_DIRECT) {
+                       /*
+                        * Silently fall back to buffered I/O for stuffed files
+                        * or if we've got a hole (see gfs2_file_direct_write).
+                        */
+                       if (iomap->type != IOMAP_MAPPED)
+                               ret = -ENOTBLK;
+                       goto out_unlock;
+               }
+               break;
+       default:
+               goto out_unlock;
        }
+
+       ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap, &mp);
+
+out_unlock:
+       if (ret && gfs2_iomap_need_write_lock(flags))
+               gfs2_write_unlock(inode);
        release_metapath(&mp);
+out:
        trace_gfs2_iomap_end(ip, iomap, ret);
        return ret;
 }
@@ -1197,8 +1201,14 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
 
-       if ((flags & (IOMAP_WRITE | IOMAP_DIRECT)) != IOMAP_WRITE)
-               goto out;
+       switch (flags & IOMAP_WRITE) {
+       case IOMAP_WRITE:
+               if (flags & IOMAP_DIRECT)
+                       return 0;
+               break;
+       default:
+                return 0;
+       }
 
        if (!gfs2_is_stuffed(ip))
                gfs2_ordered_add_inode(ip);
@@ -1231,8 +1241,8 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
        set_bit(GLF_DIRTY, &ip->i_gl->gl_flags);
 
 out_unlock:
-       gfs2_write_unlock(inode);
-out:
+       if (gfs2_iomap_need_write_lock(flags))
+               gfs2_write_unlock(inode);
        return 0;
 }