As you know, VFS layer has introduced non-block aio
flag IOCB_NOWAIT, which informs kernel to bail out
if an AIO request will block for reasons such as file
allocations, or a writeback triggered, or would block
while allocating requests while performing direct I/O.
Subsequent, pwritev2/preadv2 also can leverage this
part kernel code.
So far, ext4/xfs/btrfs have supported this feature,
I'd like to add the related code for ocfs2 file system.
Compare with v3, modify the check condition for nowait in
ocfs2_file_write_iter() function. second, add direct-io and
nowait combination check in ocfs2_file_read_iter() function.
Compare with v2, do some modification in ocfs2_overwrite_io()
function for OCFS2_INLINE_DATA_FL case.
Compare with v1, some changes are as below,
use osb pointer in ocfs2_try_rw_lock() function,
modify ocfs2_overwrite_io() function to make all error
value can be returned to the upper code,
move invoking ocfs2_overwrite_io() function from
ocfs2_file_write_iter() to ocfs2_prepare_inode_for_write(),
this change can combine acquiring the related locks.
Gang He (3):
ocfs2: add ocfs2_try_rw_lock and ocfs2_try_inode_lock
ocfs2: add ocfs2_overwrite_io function
ocfs2: nowait aio support
fs/ocfs2/dir.c | 2 +-
fs/ocfs2/dlmglue.c | 41 +++++++++++++++++---
fs/ocfs2/dlmglue.h | 6 ++-
fs/ocfs2/extent_map.c | 45 ++++++++++++++++++++++
fs/ocfs2/extent_map.h | 3 ++
fs/ocfs2/file.c | 101 +++++++++++++++++++++++++++++++++++++++----------
fs/ocfs2/mmap.c | 2 +-
fs/ocfs2/ocfs2_trace.h | 10 +++--
8 files changed, 177 insertions(+), 33 deletions(-)
--
1.8.5.6
Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
will be used in non-block IO scenarios.
Reviewed-by: Alex Chen <[email protected]>
Signed-off-by: Gang He <[email protected]>
---
fs/ocfs2/dlmglue.c | 21 +++++++++++++++++++++
fs/ocfs2/dlmglue.h | 4 ++++
2 files changed, 25 insertions(+)
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 4689940..a68efa3 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -1742,6 +1742,27 @@ int ocfs2_rw_lock(struct inode *inode, int write)
return status;
}
+int ocfs2_try_rw_lock(struct inode *inode, int write)
+{
+ int status, level;
+ struct ocfs2_lock_res *lockres;
+ struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+ mlog(0, "inode %llu try to take %s RW lock\n",
+ (unsigned long long)OCFS2_I(inode)->ip_blkno,
+ write ? "EXMODE" : "PRMODE");
+
+ if (ocfs2_mount_local(osb))
+ return 0;
+
+ lockres = &OCFS2_I(inode)->ip_rw_lockres;
+
+ level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
+
+ status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
+ return status;
+}
+
void ocfs2_rw_unlock(struct inode *inode, int write)
{
int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index a7fc18b..05910fc 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -116,6 +116,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
int ocfs2_create_new_inode_locks(struct inode *inode);
int ocfs2_drop_inode_locks(struct inode *inode);
int ocfs2_rw_lock(struct inode *inode, int write);
+int ocfs2_try_rw_lock(struct inode *inode, int write);
void ocfs2_rw_unlock(struct inode *inode, int write);
int ocfs2_open_lock(struct inode *inode);
int ocfs2_try_open_lock(struct inode *inode, int write);
@@ -140,6 +141,9 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
/* 99% of the time we don't want to supply any additional flags --
* those are for very specific cases only. */
#define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0, OI_LS_NORMAL)
+#define ocfs2_try_inode_lock(i, b, e)\
+ ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
+ OI_LS_NORMAL)
void ocfs2_inode_unlock(struct inode *inode,
int ex);
int ocfs2_super_lock(struct ocfs2_super *osb,
--
1.8.5.6
Add ocfs2_overwrite_io function, which is used to judge if
overwrite allocated blocks, otherwise, the write will bring extra
block allocation overhead.
Reviewed-by: Alex Chen <[email protected]>
Signed-off-by: Gang He <[email protected]>
---
fs/ocfs2/extent_map.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
fs/ocfs2/extent_map.h | 3 +++
2 files changed, 48 insertions(+)
diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index e4719e0..06cb964 100644
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -38,6 +38,7 @@
#include "inode.h"
#include "super.h"
#include "symlink.h"
+#include "aops.h"
#include "ocfs2_trace.h"
#include "buffer_head_io.h"
@@ -832,6 +833,50 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
return ret;
}
+/* Is IO overwriting allocated blocks? */
+int ocfs2_overwrite_io(struct inode *inode, struct buffer_head *di_bh,
+ u64 map_start, u64 map_len)
+{
+ int ret = 0, is_last;
+ u32 mapping_end, cpos;
+ struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+ struct ocfs2_extent_rec rec;
+
+ if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
+ if (ocfs2_size_fits_inline_data(di_bh, map_start + map_len))
+ return ret;
+ else
+ return -EAGAIN;
+ }
+
+ cpos = map_start >> osb->s_clustersize_bits;
+ mapping_end = ocfs2_clusters_for_bytes(inode->i_sb,
+ map_start + map_len);
+ is_last = 0;
+ while (cpos < mapping_end && !is_last) {
+ ret = ocfs2_get_clusters_nocache(inode, di_bh, cpos,
+ NULL, &rec, &is_last);
+ if (ret) {
+ mlog_errno(ret);
+ goto out;
+ }
+
+ if (rec.e_blkno == 0ULL)
+ break;
+
+ if (rec.e_flags & OCFS2_EXT_REFCOUNTED)
+ break;
+
+ cpos = le32_to_cpu(rec.e_cpos) +
+ le16_to_cpu(rec.e_leaf_clusters);
+ }
+
+ if (cpos < mapping_end)
+ ret = -EAGAIN;
+out:
+ return ret;
+}
+
int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int whence)
{
struct inode *inode = file->f_mapping->host;
diff --git a/fs/ocfs2/extent_map.h b/fs/ocfs2/extent_map.h
index 67ea57d..1057586 100644
--- a/fs/ocfs2/extent_map.h
+++ b/fs/ocfs2/extent_map.h
@@ -53,6 +53,9 @@ int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
u64 map_start, u64 map_len);
+int ocfs2_overwrite_io(struct inode *inode, struct buffer_head *di_bh,
+ u64 map_start, u64 map_len);
+
int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin);
int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster,
--
1.8.5.6
Return -EAGAIN if any of the following checks fail for
direct I/O with nowait flag:
Can not get the related locks immediately,
Blocks are not allocated at the write location, it will trigger
block allocation, this will block IO operations.
Signed-off-by: Gang He <[email protected]>
---
fs/ocfs2/dir.c | 2 +-
fs/ocfs2/dlmglue.c | 20 +++++++---
fs/ocfs2/dlmglue.h | 2 +-
fs/ocfs2/file.c | 101 +++++++++++++++++++++++++++++++++++++++----------
fs/ocfs2/mmap.c | 2 +-
fs/ocfs2/ocfs2_trace.h | 10 +++--
6 files changed, 104 insertions(+), 33 deletions(-)
diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index febe631..ea50901 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -1957,7 +1957,7 @@ int ocfs2_readdir(struct file *file, struct dir_context *ctx)
trace_ocfs2_readdir((unsigned long long)OCFS2_I(inode)->ip_blkno);
- error = ocfs2_inode_lock_atime(inode, file->f_path.mnt, &lock_level);
+ error = ocfs2_inode_lock_atime(inode, file->f_path.mnt, &lock_level, 1);
if (lock_level && error >= 0) {
/* We release EX lock which used to update atime
* and get PR lock again to reduce contention
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index a68efa3..07e169f 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2515,13 +2515,18 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
int ocfs2_inode_lock_atime(struct inode *inode,
struct vfsmount *vfsmnt,
- int *level)
+ int *level, int wait)
{
int ret;
- ret = ocfs2_inode_lock(inode, NULL, 0);
+ if (wait)
+ ret = ocfs2_inode_lock(inode, NULL, 0);
+ else
+ ret = ocfs2_try_inode_lock(inode, NULL, 0);
+
if (ret < 0) {
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
return ret;
}
@@ -2533,9 +2538,14 @@ int ocfs2_inode_lock_atime(struct inode *inode,
struct buffer_head *bh = NULL;
ocfs2_inode_unlock(inode, 0);
- ret = ocfs2_inode_lock(inode, &bh, 1);
+ if (wait)
+ ret = ocfs2_inode_lock(inode, &bh, 1);
+ else
+ ret = ocfs2_try_inode_lock(inode, &bh, 1);
+
if (ret < 0) {
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
return ret;
}
*level = 1;
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index 05910fc..c83dbb5 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -123,7 +123,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
void ocfs2_open_unlock(struct inode *inode);
int ocfs2_inode_lock_atime(struct inode *inode,
struct vfsmount *vfsmnt,
- int *level);
+ int *level, int wait);
int ocfs2_inode_lock_full_nested(struct inode *inode,
struct buffer_head **ret_bh,
int ex,
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index a1d0510..5d1784a 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -140,6 +140,8 @@ static int ocfs2_file_open(struct inode *inode, struct file *file)
spin_unlock(&oi->ip_lock);
}
+ file->f_mode |= FMODE_NOWAIT;
+
leave:
return status;
}
@@ -2132,12 +2134,12 @@ static int ocfs2_prepare_inode_for_refcount(struct inode *inode,
}
static int ocfs2_prepare_inode_for_write(struct file *file,
- loff_t pos,
- size_t count)
+ loff_t pos, size_t count, int wait)
{
- int ret = 0, meta_level = 0;
+ int ret = 0, meta_level = 0, overwrite_io = 0;
struct dentry *dentry = file->f_path.dentry;
struct inode *inode = d_inode(dentry);
+ struct buffer_head *di_bh = NULL;
loff_t end;
/*
@@ -2145,13 +2147,40 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
* if we need to make modifications here.
*/
for(;;) {
- ret = ocfs2_inode_lock(inode, NULL, meta_level);
+ if (wait)
+ ret = ocfs2_inode_lock(inode, NULL, meta_level);
+ else
+ ret = ocfs2_try_inode_lock(inode,
+ overwrite_io ? NULL : &di_bh, meta_level);
if (ret < 0) {
meta_level = -1;
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
goto out;
}
+ /*
+ * Check if IO will overwrite allocated blocks in case
+ * IOCB_NOWAIT flag is set.
+ */
+ if (!wait && !overwrite_io) {
+ overwrite_io = 1;
+ if (!down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem)) {
+ ret = -EAGAIN;
+ goto out_unlock;
+ }
+
+ ret = ocfs2_overwrite_io(inode, di_bh, pos, count);
+ brelse(di_bh);
+ di_bh = NULL;
+ up_read(&OCFS2_I(inode)->ip_alloc_sem);
+ if (ret < 0) {
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
+ goto out_unlock;
+ }
+ }
+
/* Clear suid / sgid if necessary. We do this here
* instead of later in the write path because
* remove_suid() calls ->setattr without any hint that
@@ -2199,7 +2228,9 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
out_unlock:
trace_ocfs2_prepare_inode_for_write(OCFS2_I(inode)->ip_blkno,
- pos, count);
+ pos, count, wait);
+
+ brelse(di_bh);
if (meta_level >= 0)
ocfs2_inode_unlock(inode, meta_level);
@@ -2211,7 +2242,7 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
- int direct_io, rw_level;
+ int rw_level;
ssize_t written = 0;
ssize_t ret;
size_t count = iov_iter_count(from);
@@ -2223,6 +2254,8 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
void *saved_ki_complete = NULL;
int append_write = ((iocb->ki_pos + count) >=
i_size_read(inode) ? 1 : 0);
+ int direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
+ int nowait = iocb->ki_flags & IOCB_NOWAIT ? 1 : 0;
trace_ocfs2_file_aio_write(inode, file, file->f_path.dentry,
(unsigned long long)OCFS2_I(inode)->ip_blkno,
@@ -2230,12 +2263,17 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
file->f_path.dentry->d_name.name,
(unsigned int)from->nr_segs); /* GRRRRR */
+ if (!direct_io && nowait)
+ return -EOPNOTSUPP;
+
if (count == 0)
return 0;
- direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
-
- inode_lock(inode);
+ if (nowait) {
+ if (!inode_trylock(inode))
+ return -EAGAIN;
+ } else
+ inode_lock(inode);
/*
* Concurrent O_DIRECT writes are allowed with
@@ -2244,9 +2282,13 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
*/
rw_level = (!direct_io || full_coherency || append_write);
- ret = ocfs2_rw_lock(inode, rw_level);
+ if (nowait)
+ ret = ocfs2_try_rw_lock(inode, rw_level);
+ else
+ ret = ocfs2_rw_lock(inode, rw_level);
if (ret < 0) {
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
goto out_mutex;
}
@@ -2260,9 +2302,13 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
* other nodes to drop their caches. Buffered I/O
* already does this in write_begin().
*/
- ret = ocfs2_inode_lock(inode, NULL, 1);
+ if (nowait)
+ ret = ocfs2_try_inode_lock(inode, NULL, 1);
+ else
+ ret = ocfs2_inode_lock(inode, NULL, 1);
if (ret < 0) {
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
goto out;
}
@@ -2277,9 +2323,10 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
}
count = ret;
- ret = ocfs2_prepare_inode_for_write(file, iocb->ki_pos, count);
+ ret = ocfs2_prepare_inode_for_write(file, iocb->ki_pos, count, !nowait);
if (ret < 0) {
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
goto out;
}
@@ -2355,6 +2402,8 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
int ret = 0, rw_level = -1, lock_level = 0;
struct file *filp = iocb->ki_filp;
struct inode *inode = file_inode(filp);
+ int direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
+ int nowait = iocb->ki_flags & IOCB_NOWAIT ? 1 : 0;
trace_ocfs2_file_aio_read(inode, filp, filp->f_path.dentry,
(unsigned long long)OCFS2_I(inode)->ip_blkno,
@@ -2369,14 +2418,22 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
goto bail;
}
+ if (!direct_io && nowait)
+ return -EOPNOTSUPP;
+
/*
* buffered reads protect themselves in ->readpage(). O_DIRECT reads
* need locks to protect pending reads from racing with truncate.
*/
- if (iocb->ki_flags & IOCB_DIRECT) {
- ret = ocfs2_rw_lock(inode, 0);
+ if (direct_io) {
+ if (nowait)
+ ret = ocfs2_try_rw_lock(inode, 0);
+ else
+ ret = ocfs2_rw_lock(inode, 0);
+
if (ret < 0) {
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
goto bail;
}
rw_level = 0;
@@ -2393,9 +2450,11 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
* like i_size. This allows the checks down below
* generic_file_aio_read() a chance of actually working.
*/
- ret = ocfs2_inode_lock_atime(inode, filp->f_path.mnt, &lock_level);
+ ret = ocfs2_inode_lock_atime(inode, filp->f_path.mnt, &lock_level,
+ !nowait);
if (ret < 0) {
- mlog_errno(ret);
+ if (ret != -EAGAIN)
+ mlog_errno(ret);
goto bail;
}
ocfs2_inode_unlock(inode, lock_level);
diff --git a/fs/ocfs2/mmap.c b/fs/ocfs2/mmap.c
index 098f5c7..fb9a20e 100644
--- a/fs/ocfs2/mmap.c
+++ b/fs/ocfs2/mmap.c
@@ -184,7 +184,7 @@ int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
int ret = 0, lock_level = 0;
ret = ocfs2_inode_lock_atime(file_inode(file),
- file->f_path.mnt, &lock_level);
+ file->f_path.mnt, &lock_level, 1);
if (ret < 0) {
mlog_errno(ret);
goto out;
diff --git a/fs/ocfs2/ocfs2_trace.h b/fs/ocfs2/ocfs2_trace.h
index a0b5d00..e2a11aa 100644
--- a/fs/ocfs2/ocfs2_trace.h
+++ b/fs/ocfs2/ocfs2_trace.h
@@ -1449,20 +1449,22 @@
TRACE_EVENT(ocfs2_prepare_inode_for_write,
TP_PROTO(unsigned long long ino, unsigned long long saved_pos,
- unsigned long count),
- TP_ARGS(ino, saved_pos, count),
+ unsigned long count, int wait),
+ TP_ARGS(ino, saved_pos, count, wait),
TP_STRUCT__entry(
__field(unsigned long long, ino)
__field(unsigned long long, saved_pos)
__field(unsigned long, count)
+ __field(int, wait)
),
TP_fast_assign(
__entry->ino = ino;
__entry->saved_pos = saved_pos;
__entry->count = count;
+ __entry->wait = wait;
),
- TP_printk("%llu %llu %lu", __entry->ino,
- __entry->saved_pos, __entry->count)
+ TP_printk("%llu %llu %lu %d", __entry->ino,
+ __entry->saved_pos, __entry->count, __entry->wait)
);
DEFINE_OCFS2_INT_EVENT(generic_file_aio_read_ret);
--
1.8.5.6
Hi Gang,
Looks good to me.
On 2018/1/15 17:08, Gang He wrote:
> Return -EAGAIN if any of the following checks fail for
> direct I/O with nowait flag:
> Can not get the related locks immediately,
> Blocks are not allocated at the write location, it will trigger
> block allocation, this will block IO operations.
>
> Signed-off-by: Gang He <[email protected]>
Reviewed-by: Alex Chen <[email protected]>
> ---
> fs/ocfs2/dir.c | 2 +-
> fs/ocfs2/dlmglue.c | 20 +++++++---
> fs/ocfs2/dlmglue.h | 2 +-
> fs/ocfs2/file.c | 101 +++++++++++++++++++++++++++++++++++++++----------
> fs/ocfs2/mmap.c | 2 +-
> fs/ocfs2/ocfs2_trace.h | 10 +++--
> 6 files changed, 104 insertions(+), 33 deletions(-)
>
> diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
> index febe631..ea50901 100644
> --- a/fs/ocfs2/dir.c
> +++ b/fs/ocfs2/dir.c
> @@ -1957,7 +1957,7 @@ int ocfs2_readdir(struct file *file, struct dir_context *ctx)
>
> trace_ocfs2_readdir((unsigned long long)OCFS2_I(inode)->ip_blkno);
>
> - error = ocfs2_inode_lock_atime(inode, file->f_path.mnt, &lock_level);
> + error = ocfs2_inode_lock_atime(inode, file->f_path.mnt, &lock_level, 1);
> if (lock_level && error >= 0) {
> /* We release EX lock which used to update atime
> * and get PR lock again to reduce contention
> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
> index a68efa3..07e169f 100644
> --- a/fs/ocfs2/dlmglue.c
> +++ b/fs/ocfs2/dlmglue.c
> @@ -2515,13 +2515,18 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
>
> int ocfs2_inode_lock_atime(struct inode *inode,
> struct vfsmount *vfsmnt,
> - int *level)
> + int *level, int wait)
> {
> int ret;
>
> - ret = ocfs2_inode_lock(inode, NULL, 0);
> + if (wait)
> + ret = ocfs2_inode_lock(inode, NULL, 0);
> + else
> + ret = ocfs2_try_inode_lock(inode, NULL, 0);
> +
> if (ret < 0) {
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> return ret;
> }
>
> @@ -2533,9 +2538,14 @@ int ocfs2_inode_lock_atime(struct inode *inode,
> struct buffer_head *bh = NULL;
>
> ocfs2_inode_unlock(inode, 0);
> - ret = ocfs2_inode_lock(inode, &bh, 1);
> + if (wait)
> + ret = ocfs2_inode_lock(inode, &bh, 1);
> + else
> + ret = ocfs2_try_inode_lock(inode, &bh, 1);
> +
> if (ret < 0) {
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> return ret;
> }
> *level = 1;
> diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
> index 05910fc..c83dbb5 100644
> --- a/fs/ocfs2/dlmglue.h
> +++ b/fs/ocfs2/dlmglue.h
> @@ -123,7 +123,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
> void ocfs2_open_unlock(struct inode *inode);
> int ocfs2_inode_lock_atime(struct inode *inode,
> struct vfsmount *vfsmnt,
> - int *level);
> + int *level, int wait);
> int ocfs2_inode_lock_full_nested(struct inode *inode,
> struct buffer_head **ret_bh,
> int ex,
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index a1d0510..5d1784a 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -140,6 +140,8 @@ static int ocfs2_file_open(struct inode *inode, struct file *file)
> spin_unlock(&oi->ip_lock);
> }
>
> + file->f_mode |= FMODE_NOWAIT;
> +
> leave:
> return status;
> }
> @@ -2132,12 +2134,12 @@ static int ocfs2_prepare_inode_for_refcount(struct inode *inode,
> }
>
> static int ocfs2_prepare_inode_for_write(struct file *file,
> - loff_t pos,
> - size_t count)
> + loff_t pos, size_t count, int wait)
> {
> - int ret = 0, meta_level = 0;
> + int ret = 0, meta_level = 0, overwrite_io = 0;
> struct dentry *dentry = file->f_path.dentry;
> struct inode *inode = d_inode(dentry);
> + struct buffer_head *di_bh = NULL;
> loff_t end;
>
> /*
> @@ -2145,13 +2147,40 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
> * if we need to make modifications here.
> */
> for(;;) {
> - ret = ocfs2_inode_lock(inode, NULL, meta_level);
> + if (wait)
> + ret = ocfs2_inode_lock(inode, NULL, meta_level);
> + else
> + ret = ocfs2_try_inode_lock(inode,
> + overwrite_io ? NULL : &di_bh, meta_level);
> if (ret < 0) {
> meta_level = -1;
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> goto out;
> }
>
> + /*
> + * Check if IO will overwrite allocated blocks in case
> + * IOCB_NOWAIT flag is set.
> + */
> + if (!wait && !overwrite_io) {
> + overwrite_io = 1;
> + if (!down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem)) {
> + ret = -EAGAIN;
> + goto out_unlock;
> + }
> +
> + ret = ocfs2_overwrite_io(inode, di_bh, pos, count);
> + brelse(di_bh);
> + di_bh = NULL;
> + up_read(&OCFS2_I(inode)->ip_alloc_sem);
> + if (ret < 0) {
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> + goto out_unlock;
> + }
> + }
> +
> /* Clear suid / sgid if necessary. We do this here
> * instead of later in the write path because
> * remove_suid() calls ->setattr without any hint that
> @@ -2199,7 +2228,9 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
>
> out_unlock:
> trace_ocfs2_prepare_inode_for_write(OCFS2_I(inode)->ip_blkno,
> - pos, count);
> + pos, count, wait);
> +
> + brelse(di_bh);
>
> if (meta_level >= 0)
> ocfs2_inode_unlock(inode, meta_level);
> @@ -2211,7 +2242,7 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
> static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
> struct iov_iter *from)
> {
> - int direct_io, rw_level;
> + int rw_level;
> ssize_t written = 0;
> ssize_t ret;
> size_t count = iov_iter_count(from);
> @@ -2223,6 +2254,8 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
> void *saved_ki_complete = NULL;
> int append_write = ((iocb->ki_pos + count) >=
> i_size_read(inode) ? 1 : 0);
> + int direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
> + int nowait = iocb->ki_flags & IOCB_NOWAIT ? 1 : 0;
>
> trace_ocfs2_file_aio_write(inode, file, file->f_path.dentry,
> (unsigned long long)OCFS2_I(inode)->ip_blkno,
> @@ -2230,12 +2263,17 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
> file->f_path.dentry->d_name.name,
> (unsigned int)from->nr_segs); /* GRRRRR */
>
> + if (!direct_io && nowait)
> + return -EOPNOTSUPP;
> +
> if (count == 0)
> return 0;
>
> - direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
> -
> - inode_lock(inode);
> + if (nowait) {
> + if (!inode_trylock(inode))
> + return -EAGAIN;
> + } else
> + inode_lock(inode);
>
> /*
> * Concurrent O_DIRECT writes are allowed with
> @@ -2244,9 +2282,13 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
> */
> rw_level = (!direct_io || full_coherency || append_write);
>
> - ret = ocfs2_rw_lock(inode, rw_level);
> + if (nowait)
> + ret = ocfs2_try_rw_lock(inode, rw_level);
> + else
> + ret = ocfs2_rw_lock(inode, rw_level);
> if (ret < 0) {
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> goto out_mutex;
> }
>
> @@ -2260,9 +2302,13 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
> * other nodes to drop their caches. Buffered I/O
> * already does this in write_begin().
> */
> - ret = ocfs2_inode_lock(inode, NULL, 1);
> + if (nowait)
> + ret = ocfs2_try_inode_lock(inode, NULL, 1);
> + else
> + ret = ocfs2_inode_lock(inode, NULL, 1);
> if (ret < 0) {
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> goto out;
> }
>
> @@ -2277,9 +2323,10 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
> }
> count = ret;
>
> - ret = ocfs2_prepare_inode_for_write(file, iocb->ki_pos, count);
> + ret = ocfs2_prepare_inode_for_write(file, iocb->ki_pos, count, !nowait);
> if (ret < 0) {
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> goto out;
> }
>
> @@ -2355,6 +2402,8 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
> int ret = 0, rw_level = -1, lock_level = 0;
> struct file *filp = iocb->ki_filp;
> struct inode *inode = file_inode(filp);
> + int direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
> + int nowait = iocb->ki_flags & IOCB_NOWAIT ? 1 : 0;
>
> trace_ocfs2_file_aio_read(inode, filp, filp->f_path.dentry,
> (unsigned long long)OCFS2_I(inode)->ip_blkno,
> @@ -2369,14 +2418,22 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
> goto bail;
> }
>
> + if (!direct_io && nowait)
> + return -EOPNOTSUPP;
> +
> /*
> * buffered reads protect themselves in ->readpage(). O_DIRECT reads
> * need locks to protect pending reads from racing with truncate.
> */
> - if (iocb->ki_flags & IOCB_DIRECT) {
> - ret = ocfs2_rw_lock(inode, 0);
> + if (direct_io) {
> + if (nowait)
> + ret = ocfs2_try_rw_lock(inode, 0);
> + else
> + ret = ocfs2_rw_lock(inode, 0);
> +
> if (ret < 0) {
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> goto bail;
> }
> rw_level = 0;
> @@ -2393,9 +2450,11 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
> * like i_size. This allows the checks down below
> * generic_file_aio_read() a chance of actually working.
> */
> - ret = ocfs2_inode_lock_atime(inode, filp->f_path.mnt, &lock_level);
> + ret = ocfs2_inode_lock_atime(inode, filp->f_path.mnt, &lock_level,
> + !nowait);
> if (ret < 0) {
> - mlog_errno(ret);
> + if (ret != -EAGAIN)
> + mlog_errno(ret);
> goto bail;
> }
> ocfs2_inode_unlock(inode, lock_level);
> diff --git a/fs/ocfs2/mmap.c b/fs/ocfs2/mmap.c
> index 098f5c7..fb9a20e 100644
> --- a/fs/ocfs2/mmap.c
> +++ b/fs/ocfs2/mmap.c
> @@ -184,7 +184,7 @@ int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
> int ret = 0, lock_level = 0;
>
> ret = ocfs2_inode_lock_atime(file_inode(file),
> - file->f_path.mnt, &lock_level);
> + file->f_path.mnt, &lock_level, 1);
> if (ret < 0) {
> mlog_errno(ret);
> goto out;
> diff --git a/fs/ocfs2/ocfs2_trace.h b/fs/ocfs2/ocfs2_trace.h
> index a0b5d00..e2a11aa 100644
> --- a/fs/ocfs2/ocfs2_trace.h
> +++ b/fs/ocfs2/ocfs2_trace.h
> @@ -1449,20 +1449,22 @@
>
> TRACE_EVENT(ocfs2_prepare_inode_for_write,
> TP_PROTO(unsigned long long ino, unsigned long long saved_pos,
> - unsigned long count),
> - TP_ARGS(ino, saved_pos, count),
> + unsigned long count, int wait),
> + TP_ARGS(ino, saved_pos, count, wait),
> TP_STRUCT__entry(
> __field(unsigned long long, ino)
> __field(unsigned long long, saved_pos)
> __field(unsigned long, count)
> + __field(int, wait)
> ),
> TP_fast_assign(
> __entry->ino = ino;
> __entry->saved_pos = saved_pos;
> __entry->count = count;
> + __entry->wait = wait;
> ),
> - TP_printk("%llu %llu %lu", __entry->ino,
> - __entry->saved_pos, __entry->count)
> + TP_printk("%llu %llu %lu %d", __entry->ino,
> + __entry->saved_pos, __entry->count, __entry->wait)
> );
>
> DEFINE_OCFS2_INT_EVENT(generic_file_aio_read_ret);
>