From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
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;
}
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);
+ 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)
#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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