Re: [PATCH 2/2] xfs: prevent close() from hanging on frozen filesystems

[Aditya Prakash Srivastava]

The sequencing is wrong, Please ignore

Will send a fresh series

On Fri, Jun 12, 2026 at 4:53 PM Aditya Srivastava
<aditya.ansh182@xxxxxxxxx> wrote:
>
> From: Aditya Prakash Srivastava <aditya.ansh182@xxxxxxxxx>
>
> When a file with active speculative post-EOF preallocations is closed,
> xfs_file_release() synchronously triggers xfs_free_eofblocks() to clean
> them up. This requires allocating a write transaction (xfs_trans_alloc),
> which blocks indefinitely if the filesystem is currently frozen or in the
> process of freezing, as it waits to acquire the superblock's write lock.
>
> As a result, a close() system call on a read-write file descriptor can
> hang indefinitely in percpu_rwsem_wait() until the filesystem is thawed,
> even if the file is closed by a non-writer process or after all writing
> activity has already ceased.
>
> To fix this properly and avoid any potential race conditions where a freeze
> might come in immediately after a writable check, pass the new
> XFS_TRANS_WRITECOUNT_TRYLOCK flag to xfs_trans_alloc() when freeing
> speculative preallocations in xfs_file_release().
>
> If xfs_free_eofblocks() returns -EAGAIN on a trylock failure, we cleanly
> bypass setting XFS_EOFBLOCKS_RELEASED on the inode, ensuring subsequent
> releases or the background blockgc garbage collector can successfully retry
> the cleanup once the filesystem thaws.
>
> Also, rename the flags parameter in xfs_free_eofblocks() to trans_flags as
> suggested to make its usage stand out, and update existing callers to
> pass 0 to preserve standard blocking paths.
>
> Suggested-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@xxxxxxxxx>
> ---
>  fs/xfs/xfs_bmap_util.c | 9 +++++----
>  fs/xfs/xfs_bmap_util.h | 2 +-
>  fs/xfs/xfs_file.c      | 8 +++++---
>  fs/xfs/xfs_icache.c    | 2 +-
>  fs/xfs/xfs_inode.c     | 2 +-
>  5 files changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 0ab00615f1ad..faf0630717dc 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -574,7 +574,8 @@ xfs_can_free_eofblocks(
>   */
>  int
>  xfs_free_eofblocks(
> -       struct xfs_inode        *ip)
> +       struct xfs_inode        *ip,
> +       uint                    trans_flags)
>  {
>         struct xfs_trans        *tp;
>         struct xfs_mount        *mp = ip->i_mount;
> @@ -604,9 +605,9 @@ xfs_free_eofblocks(
>                 return 0;
>         }
>
> -       error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
> +       error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, trans_flags, &tp);
>         if (error) {
> -               ASSERT(xfs_is_shutdown(mp));
> +               ASSERT(error == -EAGAIN || xfs_is_shutdown(mp));
>                 return error;
>         }
>
> @@ -928,7 +929,7 @@ xfs_prepare_shift(
>          * into the accessible region of the file.
>          */
>         if (xfs_can_free_eofblocks(ip)) {
> -               error = xfs_free_eofblocks(ip);
> +               error = xfs_free_eofblocks(ip, 0);
>                 if (error)
>                         return error;
>         }
> diff --git a/fs/xfs/xfs_bmap_util.h b/fs/xfs/xfs_bmap_util.h
> index c477b3361630..c13774aa0892 100644
> --- a/fs/xfs/xfs_bmap_util.h
> +++ b/fs/xfs/xfs_bmap_util.h
> @@ -66,7 +66,7 @@ int   xfs_insert_file_space(struct xfs_inode *, xfs_off_t offset,
>
>  /* EOF block manipulation functions */
>  bool   xfs_can_free_eofblocks(struct xfs_inode *ip);
> -int    xfs_free_eofblocks(struct xfs_inode *ip);
> +int    xfs_free_eofblocks(struct xfs_inode *ip, uint trans_flags);
>
>  int    xfs_swap_extents(struct xfs_inode *ip, struct xfs_inode *tip,
>                          struct xfs_swapext *sx);
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 845a97c9b063..76c9b2fe7c51 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1806,9 +1806,11 @@ xfs_file_release(
>          */
>         if (!xfs_iflags_test(ip, XFS_EOFBLOCKS_RELEASED) &&
>             xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
> -               if (xfs_can_free_eofblocks(ip) &&
> -                   !xfs_iflags_test_and_set(ip, XFS_EOFBLOCKS_RELEASED))
> -                       xfs_free_eofblocks(ip);
> +               if (!xfs_iflags_test(ip, XFS_EOFBLOCKS_RELEASED) &&
> +                   xfs_can_free_eofblocks(ip) &&
> +                   !xfs_free_eofblocks(ip, XFS_TRANS_WRITECOUNT_TRYLOCK))
> +                       xfs_iflags_set(ip, XFS_EOFBLOCKS_RELEASED);
> +
>                 xfs_iunlock(ip, XFS_IOLOCK_EXCL);
>         }
>
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 2040a9292ee6..c575b4acb24c 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -1259,7 +1259,7 @@ xfs_inode_free_eofblocks(
>         *lockflags |= XFS_IOLOCK_EXCL;
>
>         if (xfs_can_free_eofblocks(ip))
> -               return xfs_free_eofblocks(ip);
> +               return xfs_free_eofblocks(ip, 0);
>
>         /* inode could be preallocated */
>         trace_xfs_inode_free_eofblocks_invalid(ip);
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 9978ac1422fc..1c75f51af4d7 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -1423,7 +1423,7 @@ xfs_inactive(
>                  * reference to the inode at this point anyways.
>                  */
>                 if (xfs_can_free_eofblocks(ip))
> -                       error = xfs_free_eofblocks(ip);
> +                       error = xfs_free_eofblocks(ip, 0);
>
>                 goto out;
>         }
> --
> 2.47.3
>