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authorAndreas Gruenbacher2019-04-29 20:50:30 +0100
committerAndreas Gruenbacher2019-05-07 23:39:15 +0200
commitd0a22a4b03b8475b7aa3fa41243c26c291407844 (patch)
treeaf68f7f35e0a354aa370d130e9e79b757783b36d /fs/gfs2/bmap.c
parent8f91821990fd6f170a5dca79697a441181a41b16 (diff)
gfs2: Fix iomap write page reclaim deadlock
Since commit 64bc06bb32ee ("gfs2: iomap buffered write support"), gfs2 is doing buffered writes by starting a transaction in iomap_begin, writing a range of pages, and ending that transaction in iomap_end. This approach suffers from two problems: (1) Any allocations necessary for the write are done in iomap_begin, so when the data aren't journaled, there is no need for keeping the transaction open until iomap_end. (2) Transactions keep the gfs2 log flush lock held. When iomap_file_buffered_write calls balance_dirty_pages, this can end up calling gfs2_write_inode, which will try to flush the log. This requires taking the log flush lock which is already held, resulting in a deadlock. Fix both of these issues by not keeping transactions open from iomap_begin to iomap_end. Instead, start a small transaction in page_prepare and end it in page_done when necessary. Reported-by: Edwin Török <edvin.torok@citrix.com> Fixes: 64bc06bb32ee ("gfs2: iomap buffered write support") Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Diffstat (limited to 'fs/gfs2/bmap.c')
-rw-r--r--fs/gfs2/bmap.c88
1 files changed, 48 insertions, 40 deletions
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 6f1f0d30fe29..f42718dd292f 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -991,17 +991,28 @@ static void gfs2_write_unlock(struct inode *inode)
gfs2_glock_dq_uninit(&ip->i_gh);
}
+static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos,
+ unsigned len, struct iomap *iomap)
+{
+ struct gfs2_sbd *sdp = GFS2_SB(inode);
+
+ return gfs2_trans_begin(sdp, RES_DINODE + (len >> inode->i_blkbits), 0);
+}
+
static void gfs2_iomap_page_done(struct inode *inode, loff_t pos,
unsigned copied, struct page *page,
struct iomap *iomap)
{
struct gfs2_inode *ip = GFS2_I(inode);
+ struct gfs2_sbd *sdp = GFS2_SB(inode);
- if (page)
+ if (page && !gfs2_is_stuffed(ip))
gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied);
+ gfs2_trans_end(sdp);
}
static const struct iomap_page_ops gfs2_iomap_page_ops = {
+ .page_prepare = gfs2_iomap_page_prepare,
.page_done = gfs2_iomap_page_done,
};
@@ -1057,31 +1068,45 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
if (alloc_required)
rblocks += gfs2_rg_blocks(ip, data_blocks + ind_blocks);
- ret = gfs2_trans_begin(sdp, rblocks, iomap->length >> inode->i_blkbits);
- if (ret)
- goto out_trans_fail;
+ if (unstuff || iomap->type == IOMAP_HOLE) {
+ struct gfs2_trans *tr;
- if (unstuff) {
- ret = gfs2_unstuff_dinode(ip, NULL);
+ ret = gfs2_trans_begin(sdp, rblocks,
+ iomap->length >> inode->i_blkbits);
if (ret)
- goto out_trans_end;
- release_metapath(mp);
- ret = gfs2_iomap_get(inode, iomap->offset, iomap->length,
- flags, iomap, mp);
- if (ret)
- goto out_trans_end;
- }
+ goto out_trans_fail;
- if (iomap->type == IOMAP_HOLE) {
- ret = gfs2_iomap_alloc(inode, iomap, flags, mp);
- if (ret) {
- gfs2_trans_end(sdp);
- gfs2_inplace_release(ip);
- punch_hole(ip, iomap->offset, iomap->length);
- goto out_qunlock;
+ if (unstuff) {
+ ret = gfs2_unstuff_dinode(ip, NULL);
+ if (ret)
+ goto out_trans_end;
+ release_metapath(mp);
+ ret = gfs2_iomap_get(inode, iomap->offset,
+ iomap->length, flags, iomap, mp);
+ if (ret)
+ goto out_trans_end;
+ }
+
+ if (iomap->type == IOMAP_HOLE) {
+ ret = gfs2_iomap_alloc(inode, iomap, flags, mp);
+ if (ret) {
+ gfs2_trans_end(sdp);
+ gfs2_inplace_release(ip);
+ punch_hole(ip, iomap->offset, iomap->length);
+ goto out_qunlock;
+ }
}
+
+ tr = current->journal_info;
+ if (tr->tr_num_buf_new)
+ __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+ else
+ gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[0]);
+
+ gfs2_trans_end(sdp);
}
- if (!gfs2_is_stuffed(ip) && gfs2_is_jdata(ip))
+
+ if (gfs2_is_stuffed(ip) || gfs2_is_jdata(ip))
iomap->page_ops = &gfs2_iomap_page_ops;
return 0;
@@ -1121,10 +1146,6 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
iomap->type != IOMAP_MAPPED)
ret = -ENOTBLK;
}
- if (!ret) {
- get_bh(mp.mp_bh[0]);
- iomap->private = mp.mp_bh[0];
- }
release_metapath(&mp);
trace_gfs2_iomap_end(ip, iomap, ret);
return ret;
@@ -1135,27 +1156,16 @@ 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);
- struct gfs2_trans *tr = current->journal_info;
- struct buffer_head *dibh = iomap->private;
if ((flags & (IOMAP_WRITE | IOMAP_DIRECT)) != IOMAP_WRITE)
goto out;
- if (iomap->type != IOMAP_INLINE) {
+ if (!gfs2_is_stuffed(ip))
gfs2_ordered_add_inode(ip);
- if (tr->tr_num_buf_new)
- __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
- else
- gfs2_trans_add_meta(ip->i_gl, dibh);
- }
-
- if (inode == sdp->sd_rindex) {
+ if (inode == sdp->sd_rindex)
adjust_fs_space(inode);
- sdp->sd_rindex_uptodate = 0;
- }
- gfs2_trans_end(sdp);
gfs2_inplace_release(ip);
if (length != written && (iomap->flags & IOMAP_F_NEW)) {
@@ -1175,8 +1185,6 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
gfs2_write_unlock(inode);
out:
- if (dibh)
- brelse(dibh);
return 0;
}