On Mon, Feb 13, 2017 at 08:46:02PM -0600, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Send the whole patchset to linux-xfs, please.
> If IOCB_NONBLOCKING is set:
> + Check if writing beyond end of file, if yes return EAGAIN
> - check if writing to a hole which does not have allocated
> file blocks.
> - Check if i_rwsem is immediately lockable in xfs_rw_ilock()
>
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
> ---
> fs/xfs/xfs_file.c | 36 ++++++++++++++++++++++++++++++++----
> fs/xfs/xfs_inode.h | 2 ++
> 2 files changed, 34 insertions(+), 4 deletions(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 9a5d64b..42f055f 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -51,14 +51,20 @@ static const struct vm_operations_struct xfs_file_vm_ops;
> * Locking primitives for read and write IO paths to ensure we consistently use
> * and order the inode->i_mutex, ip->i_lock and ip->i_iolock.
> */
> -static inline void
> +static inline int
> xfs_rw_ilock(
> struct xfs_inode *ip,
> int type)
> {
> - if (type & XFS_IOLOCK_EXCL)
> - inode_lock(VFS_I(ip));
> + if (type & XFS_IOLOCK_EXCL) {
> + if ((type & XFS_IOLOCK_NONBLOCKING) &&
> + !inode_trylock(VFS_I(ip)))
> + return -EAGAIN;
> + else
> + inode_lock(VFS_I(ip));
> + }
> xfs_ilock(ip, type);
> + return 0;
This function went away in 4.10-rc1.
> }
>
> static inline void
> @@ -418,6 +424,24 @@ xfs_file_aio_write_checks(
> if (error <= 0)
> return error;
>
> + if (iocb->ki_flags & IOCB_NONBLOCKING) {
> + struct xfs_bmbt_irec imap;
> + xfs_fileoff_t offset_fsb, end_fsb;
> + int nimaps = 1, ret = 0;
> + end_fsb = XFS_B_TO_FSB(ip->i_mount, iocb->ki_pos + count);
> + if (XFS_B_TO_FSB(ip->i_mount, i_size_read(inode)) < end_fsb)
> + return -EAGAIN;
> + /* Check if it is an unallocated hole */
> + offset_fsb = XFS_B_TO_FSBT(ip->i_mount, iocb->ki_pos);
> +
> + ret = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
> + &nimaps, 0);
You need to hold the ilock to call _bmapi_read, and I don't think
it's held here. Did you CONFIG_XFS_DEBUG=y?
> + if (ret)
> + return ret;
> + if (!nimaps || imap.br_startblock == HOLESTARTBLOCK)
> + return -EAGAIN;
> + }
> +
> error = xfs_break_layouts(inode, iolock, true);
> if (error)
> return error;
> @@ -555,11 +579,15 @@ xfs_file_dio_aio_write(
> ((iocb->ki_pos + count) & mp->m_blockmask)) {
> unaligned_io = 1;
> iolock = XFS_IOLOCK_EXCL;
> + if (iocb->ki_flags & IOCB_NONBLOCKING)
> + iolock |= XFS_IOLOCK_NONBLOCKING;
> } else {
> iolock = XFS_IOLOCK_SHARED;
> }
>
> - xfs_rw_ilock(ip, iolock);
> + ret = xfs_rw_ilock(ip, iolock);
> + if (ret)
> + return ret;
>
> ret = xfs_file_aio_write_checks(iocb, from, &iolock);
> if (ret)
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index 71e8a81..1a2d5eb 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -283,6 +283,7 @@ static inline void xfs_ifunlock(struct xfs_inode *ip)
> #define XFS_ILOCK_SHARED (1<<3)
> #define XFS_MMAPLOCK_EXCL (1<<4)
> #define XFS_MMAPLOCK_SHARED (1<<5)
> +#define XFS_IOLOCK_NONBLOCKING (1<<6)
What is the expected behavior if this is passed directly to xfs_ilock?
--D
>
> #define XFS_LOCK_MASK (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED \
> | XFS_ILOCK_EXCL | XFS_ILOCK_SHARED \
> @@ -291,6 +292,7 @@ static inline void xfs_ifunlock(struct xfs_inode *ip)
> #define XFS_LOCK_FLAGS \
> { XFS_IOLOCK_EXCL, "IOLOCK_EXCL" }, \
> { XFS_IOLOCK_SHARED, "IOLOCK_SHARED" }, \
> + { XFS_IOLOCK_NONBLOCKING, "IOLOCK_NONBLOCKING" }, \
> { XFS_ILOCK_EXCL, "ILOCK_EXCL" }, \
> { XFS_ILOCK_SHARED, "ILOCK_SHARED" }, \
> { XFS_MMAPLOCK_EXCL, "MMAPLOCK_EXCL" }, \
> --
> 2.10.2
>
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