4 files changed, 87 insertions, 4 deletions

diff --git a/fs/xfs/xfs_dquot.h b/fs/xfs/xfs_dquot.h
index 68a68f704837..c24c67e22a2a 100644
--- a/fs/xfs/xfs_dquot.h
+++ b/fs/xfs/xfs_dquot.h
@@ -139,6 +139,21 @@ static inline xfs_dquot_t *xfs_inode_dquot(struct xfs_inode *ip, int type)
         }
 }
 
+/*
+ * Check whether a dquot is under low free space conditions. We assume the quota
+ * is enabled and enforced.
+ */
+static inline bool xfs_dquot_lowsp(struct xfs_dquot *dqp)
+{
+        int64_t freesp;
+
+        freesp = be64_to_cpu(dqp->q_core.d_blk_hardlimit) - dqp->q_res_bcount;
+        if (freesp < dqp->q_low_space[XFS_QLOWSP_1_PCNT])
+                return true;
+
+        return false;
+}
+
 #define XFS_DQ_IS_LOCKED(dqp)   (mutex_is_locked(&((dqp)->q_qlock)))
 #define XFS_DQ_IS_DIRTY(dqp)    ((dqp)->dq_flags & XFS_DQ_DIRTY)
 #define XFS_QM_ISUDQ(dqp)       ((dqp)->dq_flags & XFS_DQ_USER)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 181605da08e4..fcf91a22f5d8 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -38,6 +38,7 @@
 #include "xfs_trace.h"
 #include "xfs_log.h"
 #include "xfs_dinode.h"
+#include "xfs_icache.h"
 
 #include <linux/aio.h>
 #include <linux/dcache.h>
@@ -689,14 +690,28 @@ write_retry:
         ret = generic_perform_write(file, from, pos);
         if (likely(ret >= 0))
                 iocb->ki_pos = pos + ret;
+
         /*
-         * If we just got an ENOSPC, try to write back all dirty inodes to
-         * convert delalloc space to free up some of the excess reserved
-         * metadata space.
+         * If we hit a space limit, try to free up some lingering preallocated
+         * space before returning an error. In the case of ENOSPC, first try to
+         * write back all dirty inodes to free up some of the excess reserved
+         * metadata space. This reduces the chances that the eofblocks scan
+         * waits on dirty mappings. Since xfs_flush_inodes() is serialized, this
+         * also behaves as a filter to prevent too many eofblocks scans from
+         * running at the same time.
          */
-        if (ret == -ENOSPC && !enospc) {
+        if (ret == -EDQUOT && !enospc) {
+                enospc = xfs_inode_free_quota_eofblocks(ip);
+                if (enospc)
+                        goto write_retry;
+        } else if (ret == -ENOSPC && !enospc) {
+                struct xfs_eofblocks eofb = {0};
+
                 enospc = 1;
                 xfs_flush_inodes(ip->i_mount);
+                eofb.eof_scan_owner = ip->i_ino; /* for locking */
+                eofb.eof_flags = XFS_EOF_FLAGS_SYNC;
+                xfs_icache_free_eofblocks(ip->i_mount, &eofb);
                 goto write_retry;
         }
 
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 43452081b705..981b2cf51985 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -33,6 +33,9 @@
 #include "xfs_trace.h"
 #include "xfs_icache.h"
 #include "xfs_bmap_util.h"
+#include "xfs_quota.h"
+#include "xfs_dquot_item.h"
+#include "xfs_dquot.h"
 
 #include <linux/kthread.h>
 #include <linux/freezer.h>
@@ -1300,6 +1303,55 @@ xfs_icache_free_eofblocks(
                                          eofb, XFS_ICI_EOFBLOCKS_TAG);
 }
 
+/*
+ * Run eofblocks scans on the quotas applicable to the inode. For inodes with
+ * multiple quotas, we don't know exactly which quota caused an allocation
+ * failure. We make a best effort by including each quota under low free space
+ * conditions (less than 1% free space) in the scan.
+ */
+int
+xfs_inode_free_quota_eofblocks(
+        struct xfs_inode *ip)
+{
+        int scan = 0;
+        struct xfs_eofblocks eofb = {0};
+        struct xfs_dquot *dq;
+
+        ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+
+        /*
+         * Set the scan owner to avoid a potential livelock. Otherwise, the scan
+         * can repeatedly trylock on the inode we're currently processing. We
+         * run a sync scan to increase effectiveness and use the union filter to
+         * cover all applicable quotas in a single scan.
+         */
+        eofb.eof_scan_owner = ip->i_ino;
+        eofb.eof_flags = XFS_EOF_FLAGS_UNION|XFS_EOF_FLAGS_SYNC;
+
+        if (XFS_IS_UQUOTA_ENFORCED(ip->i_mount)) {
+                dq = xfs_inode_dquot(ip, XFS_DQ_USER);
+                if (dq && xfs_dquot_lowsp(dq)) {
+                        eofb.eof_uid = VFS_I(ip)->i_uid;
+                        eofb.eof_flags |= XFS_EOF_FLAGS_UID;
+                        scan = 1;
+                }
+        }
+
+        if (XFS_IS_GQUOTA_ENFORCED(ip->i_mount)) {
+                dq = xfs_inode_dquot(ip, XFS_DQ_GROUP);
+                if (dq && xfs_dquot_lowsp(dq)) {
+                        eofb.eof_gid = VFS_I(ip)->i_gid;
+                        eofb.eof_flags |= XFS_EOF_FLAGS_GID;
+                        scan = 1;
+                }
+        }
+
+        if (scan)
+                xfs_icache_free_eofblocks(ip->i_mount, &eofb);
+
+        return scan;
+}
+
 void
 xfs_inode_set_eofblocks_tag(
         xfs_inode_t     *ip)
diff --git a/fs/xfs/xfs_icache.h b/fs/xfs/xfs_icache.h
index 98687af6a99d..46748b86b12f 100644
--- a/fs/xfs/xfs_icache.h
+++ b/fs/xfs/xfs_icache.h
@@ -58,6 +58,7 @@ void xfs_inode_set_reclaim_tag(struct xfs_inode *ip);
 void xfs_inode_set_eofblocks_tag(struct xfs_inode *ip);
 void xfs_inode_clear_eofblocks_tag(struct xfs_inode *ip);
 int xfs_icache_free_eofblocks(struct xfs_mount *, struct xfs_eofblocks *);
+int xfs_inode_free_quota_eofblocks(struct xfs_inode *ip);
 void xfs_eofblocks_worker(struct work_struct *);
 
 int xfs_inode_ag_iterator(struct xfs_mount *mp,