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Optimize the read code if a file is not memory mapped.
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@prasadsom
prasadsom committed Oct 12, 2010
1 parent 29d9931 commit df3f362
Showing 1 changed file with 112 additions and 82 deletions.
194 changes: 112 additions & 82 deletions module/lzfs_vnops.c
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Original file line number Diff line number Diff line change
Expand Up @@ -609,6 +609,44 @@ int lzfs_vnop_fsync(struct file *filep, struct dentry *dentry, int datasync)
return err;
}

/* XXX --> Internal function used by lzfs_vnop_readlink and lzfs_readpage
*
* Performs the read operation
*
* Explanation of parameters
* buf = buffer pointer to data
* len = length of the data
* pos = offest within file to wite
* segment = indicates whether buf pointer points to
* user space buffer or kernel buffer.
* */
static inline ssize_t lzfs_read(vnode_t *vp, const char *buf, ssize_t len,
loff_t pos, uio_seg_t segment)
{
int err;

struct iovec iov = {
.iov_base = (void *) buf,
.iov_len = len,
};

uio_t uio = {
.uio_iov = &iov,
.uio_iovcnt = 1,
.uio_loffset = (offset_t) pos,
.uio_resid = len,
.uio_segflg = segment,
};

const cred_t *cred = get_current_cred();

err = zfs_read(vp, &uio, 0, (cred_t *) cred, NULL);
put_cred(cred);
if (unlikely(err))
return -err;
return (len - uio.uio_resid);
}

int copy_data(read_descriptor_t *desc, struct page *page,
unsigned long offset, unsigned long size)
{
Expand Down Expand Up @@ -636,11 +674,7 @@ int copy_data(read_descriptor_t *desc, struct page *page,
ssize_t
lzfs_vnop_read (struct file *filep, char __user *buf, size_t len, loff_t *ppos)
{
struct iovec iov = { .iov_base = buf, .iov_len = len };
int err;
const cred_t *cred = get_current_cred();
vnode_t *vp = NULL;
uio_t uio;
loff_t isize;
ssize_t size;

Expand All @@ -655,15 +689,25 @@ lzfs_vnop_read (struct file *filep, char __user *buf, size_t len, loff_t *ppos)
unsigned int prev_offset;
read_descriptor_t desc;

ENTRY;
vp = LZFS_ITOV(inode);

if (likely(!(vp->v_flag & VMMAPPED))) {
/* file is not memory mmapped, pass read directly to ZFS */
ssize_t rc;
rc = lzfs_read(vp, buf, len, *ppos, UIO_USERSPACE);
if (likely(rc > 0))
*ppos += rc;
tsd_exit();
EXIT;
return rc;
}

desc.written = 0;
desc.arg.buf = buf;
desc.count = len;
desc.error = 0;

ENTRY;

index = *ppos >> PAGE_CACHE_SHIFT;
prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE - 1);
Expand Down Expand Up @@ -768,22 +812,13 @@ lzfs_vnop_read (struct file *filep, char __user *buf, size_t len, loff_t *ppos)
if (offset + size > isize)
size = isize - desc.written;


iov.iov_base = desc.arg.buf;
iov.iov_len = size;

uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_loffset = (offset_t) *ppos;
uio.uio_resid = size;
uio.uio_segflg = UIO_USERSPACE;
err = zfs_read(vp, &uio, 0,(cred_t *) cred, NULL);
if (unlikely(err)) {
err = -err;
goto out_error;
ret = lzfs_read(vp, desc.arg.buf, size, *ppos, UIO_USERSPACE);
if (unlikely(ret < 0)) {
tsd_exit();
EXIT;
return ret;
}

ret = size - uio.uio_resid;
desc.count = desc.count - ret;
desc.written += ret;
desc.arg.buf += ret;
Expand All @@ -805,17 +840,10 @@ lzfs_vnop_read (struct file *filep, char __user *buf, size_t len, loff_t *ppos)

out:
// *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;

zfs_file_accessed(vp);
put_cred(cred);
tsd_exit();
EXIT;
return ((ssize_t) (desc.written));
out_error:
put_cred(cred);
tsd_exit();
EXIT;
return err;
}

/* XXX --> Internal function used by lzfs_vnop_write and lzfs_writepage
Expand All @@ -830,27 +858,32 @@ lzfs_vnop_read (struct file *filep, char __user *buf, size_t len, loff_t *ppos)
* segment = indicates whether buf pointer points to
* user space buffer or kernel buffer.
* */
ssize_t lzfs_write(vnode_t *vp, unsigned int file_flags,
static inline ssize_t lzfs_write(vnode_t *vp, unsigned int file_flags,
const char *buf, ssize_t len, loff_t pos, uio_seg_t segment)
{
uio_t uio;
const cred_t *cred = get_current_cred();
struct iovec iov;
int err;

iov.iov_base = (void *) buf;
iov.iov_len = len;
int err;

struct iovec iov = {
.iov_base = (void *) buf,
.iov_len = len,
};

uio_t uio = {
.uio_iov = &iov,
.uio_resid = len,
.uio_iovcnt = 1,
.uio_loffset = (offset_t)(pos),
.uio_limit = MAXOFFSET_T,
.uio_segflg = segment,
};

uio.uio_iov = &iov;
uio.uio_resid = len;
uio.uio_iovcnt = 1;
uio.uio_loffset = (offset_t)(pos);
uio.uio_limit = MAXOFFSET_T;
uio.uio_segflg = segment;
const cred_t *cred = get_current_cred();

err = zfs_write(vp, &uio, file_flags, (cred_t *)cred, NULL);
put_cred(cred);
return err;
if (unlikely(err))
return -err;
return (len - uio.uio_resid);
}

ssize_t
Expand Down Expand Up @@ -878,16 +911,15 @@ lzfs_vnop_write (struct file *filep, const char __user *buf, size_t len,

vp = LZFS_ITOV(inode);

if (!(vp->v_flag & VMMAPPED)) {
/* file is not memory mmapped, pass read directly to ZFS */
err = lzfs_write(vp, filep->f_flags, buf, len, *ppos, UIO_USERSPACE);
if (unlikely(err)) {
err = -err;
goto out_error;
}
*ppos += len;
written = len;
goto out_success;
if (likely(!(vp->v_flag & VMMAPPED))) {
/* file is not memory mmapped, pass write directly to ZFS */
ssize_t rc;
rc = lzfs_write(vp, filep->f_flags, buf, len, *ppos, UIO_USERSPACE);
if (likely(rc > 0))
*ppos += rc;
tsd_exit();
EXIT;
return rc;
}

i_size = i_size_read(inode);
Expand Down Expand Up @@ -947,6 +979,7 @@ lzfs_vnop_write (struct file *filep, const char __user *buf, size_t len,

/* do i need to modify the inode size */
SetPageUptodate(page);
ClearPageError(page);
// set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
Expand All @@ -968,21 +1001,20 @@ lzfs_vnop_write (struct file *filep, const char __user *buf, size_t len,
continue;

no_cached_page:
err = lzfs_write(vp, filep->f_flags, user_buf, size, *ppos, UIO_USERSPACE);
if (unlikely(err)) {
err = -err;
size = lzfs_write(vp, filep->f_flags, user_buf, size, *ppos, UIO_USERSPACE);
if (unlikely(size < 0)) {
err = size;
goto out_error;
}

*ppos += size;
*ppos += size;
pos_append += size;
user_buf += size;
written += size;
index = *ppos >> PAGE_CACHE_SHIFT;
offset = 0;
user_buf += size;
written += size;
index = *ppos >> PAGE_CACHE_SHIFT;
offset = 0;
}

out_success:
tsd_exit();
EXIT;
return ((ssize_t) written);
Expand Down Expand Up @@ -1091,6 +1123,7 @@ static int lzfs_readpage(struct file *file, struct page *page)
char *buf = NULL;
vnode_t *vp = NULL;
unsigned long fillsize = 0;
ssize_t rc;
struct iovec iov;
uio_t uio;

Expand All @@ -1106,7 +1139,8 @@ static int lzfs_readpage(struct file *file, struct page *page)
PAGE_CACHE_SHIFT)) {
zero_user(page, 0, PAGE_CACHE_SIZE);
printk(KERN_ERR "Read outside i_size - truncated?");
goto done;
SetPageUptodate(page);
goto out;
}

if (NULL == (buf = kmap(page))) {
Expand All @@ -1121,18 +1155,8 @@ static int lzfs_readpage(struct file *file, struct page *page)
i_size -= offset;
fillsize = i_size > PAGE_CACHE_SIZE ? PAGE_CACHE_SIZE : i_size;

iov.iov_base = buf;
iov.iov_len = fillsize;

uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_loffset = (offset_t)(offset);
uio.uio_resid = fillsize;
uio.uio_segflg = UIO_SYSSPACE;

err = zfs_read(vp, &uio, 0, (cred_t *) cred, NULL);
if (err) {
SetPageError(page);
rc = lzfs_read(vp, buf, fillsize, offset, UIO_SYSSPACE);
if (unlikely(rc < 0)) {
fillsize = 0;
err = -EIO;
}
Expand All @@ -1141,14 +1165,17 @@ static int lzfs_readpage(struct file *file, struct page *page)
if (fillsize < PAGE_CACHE_SIZE)
memset(buf + fillsize, 0, PAGE_CACHE_SIZE - fillsize);

if (err == 0)
if (!err) {
SetPageUptodate(page);
ClearPageError(page);
flush_dcache_page(page);
} else {
ClearPageUptodate(page);
SetPageError(page);
}

flush_dcache_page(page);
kunmap(page);

done:
SetPageUptodate(page);
out:
unlock_page(page);
// printk(KERN_ERR "%s: <==\n", __FUNCTION__);
Expand Down Expand Up @@ -1203,13 +1230,16 @@ static int lzfs_writepage(struct page *page, struct writeback_control *wbc)
* to the end of the file, but the we are in writepage and data
* should be written to same offset that we provide to zfs_write.
* */
err = lzfs_write(vp, filep->f_flags & ~FAPPEND, buf, len, offset, UIO_SYSSPACE);
if (err) {
len = lzfs_write(vp, filep->f_flags & ~FAPPEND, buf, len, offset, UIO_SYSSPACE);
if (unlikely(len < 0)) {
ClearPageUptodate(page);
SetPageError(page);
err = -EIO;
}
} else {
SetPageUptodate(page);
ClearPageError(page);
}
kunmap(page);
SetPageUptodate(page);
out:
// page_clear_dirty(page);
unlock_page(page);
Expand Down

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