#include <linux/swap.h>
#include <linux/gfs2_ondisk.h>
#include <linux/lm_interface.h>
+#include <linux/swap.h>
#include "gfs2.h"
#include "incore.h"
#include "quota.h"
#include "trans.h"
#include "rgrp.h"
-#include "ops_file.h"
#include "super.h"
#include "util.h"
#include "glops.h"
/**
- * gfs2_readpage - readpage with locking
- * @file: The file to read a page for. N.B. This may be NULL if we are
- * reading an internal file.
+ * __gfs2_readpage - readpage
+ * @file: The file to read a page for
* @page: The page to read
*
- * Returns: errno
+ * This is the core of gfs2's readpage. Its used by the internal file
+ * reading code as in that case we already hold the glock. Also its
+ * called by gfs2_readpage() once the required lock has been granted.
+ *
*/
-static int gfs2_readpage(struct file *file, struct page *page)
+static int __gfs2_readpage(void *file, struct page *page)
{
struct gfs2_inode *ip = GFS2_I(page->mapping->host);
struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
- struct gfs2_file *gf = NULL;
- struct gfs2_holder gh;
int error;
- int do_unlock = 0;
-
- if (likely(file != &gfs2_internal_file_sentinel)) {
- if (file) {
- gf = file->private_data;
- if (test_bit(GFF_EXLOCK, &gf->f_flags))
- /* gfs2_sharewrite_fault has grabbed the ip->i_gl already */
- goto skip_lock;
- }
- gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
- do_unlock = 1;
- error = gfs2_glock_nq_atime(&gh);
- if (unlikely(error))
- goto out_unlock;
- }
-skip_lock:
if (gfs2_is_stuffed(ip)) {
error = stuffed_readpage(ip, page);
unlock_page(page);
- } else
+ } else {
error = mpage_readpage(page, gfs2_get_block);
+ }
if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
- error = -EIO;
+ return -EIO;
- if (do_unlock) {
- gfs2_glock_dq_m(1, &gh);
- gfs2_holder_uninit(&gh);
+ return error;
+}
+
+/**
+ * gfs2_readpage - read a page of a file
+ * @file: The file to read
+ * @page: The page of the file
+ *
+ * This deals with the locking required. We use a trylock in order to
+ * avoid the page lock / glock ordering problems returning AOP_TRUNCATED_PAGE
+ * in the event that we are unable to get the lock.
+ */
+
+static int gfs2_readpage(struct file *file, struct page *page)
+{
+ struct gfs2_inode *ip = GFS2_I(page->mapping->host);
+ struct gfs2_holder gh;
+ int error;
+
+ gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
+ error = gfs2_glock_nq_atime(&gh);
+ if (unlikely(error)) {
+ unlock_page(page);
+ goto out;
}
+ error = __gfs2_readpage(file, page);
+ gfs2_glock_dq(&gh);
out:
- return error;
-out_unlock:
- unlock_page(page);
+ gfs2_holder_uninit(&gh);
if (error == GLR_TRYFAILED) {
- error = AOP_TRUNCATED_PAGE;
yield();
+ return AOP_TRUNCATED_PAGE;
}
- if (do_unlock)
- gfs2_holder_uninit(&gh);
- goto out;
+ return error;
+}
+
+/**
+ * gfs2_internal_read - read an internal file
+ * @ip: The gfs2 inode
+ * @ra_state: The readahead state (or NULL for no readahead)
+ * @buf: The buffer to fill
+ * @pos: The file position
+ * @size: The amount to read
+ *
+ */
+
+int gfs2_internal_read(struct gfs2_inode *ip, struct file_ra_state *ra_state,
+ char *buf, loff_t *pos, unsigned size)
+{
+ struct address_space *mapping = ip->i_inode.i_mapping;
+ unsigned long index = *pos / PAGE_CACHE_SIZE;
+ unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
+ unsigned copied = 0;
+ unsigned amt;
+ struct page *page;
+ void *p;
+
+ do {
+ amt = size - copied;
+ if (offset + size > PAGE_CACHE_SIZE)
+ amt = PAGE_CACHE_SIZE - offset;
+ page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+ p = kmap_atomic(page, KM_USER0);
+ memcpy(buf + copied, p + offset, amt);
+ kunmap_atomic(p, KM_USER0);
+ mark_page_accessed(page);
+ page_cache_release(page);
+ copied += amt;
+ index++;
+ offset = 0;
+ } while(copied < size);
+ (*pos) += size;
+ return size;
}
/**
* 2. We don't handle stuffed files here we let readpage do the honours.
* 3. mpage_readpages() does most of the heavy lifting in the common case.
* 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
- * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
- * well as read-ahead.
*/
+
static int gfs2_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode);
struct gfs2_holder gh;
- int ret = 0;
- int do_unlock = 0;
-
- if (likely(file != &gfs2_internal_file_sentinel)) {
- if (file) {
- struct gfs2_file *gf = file->private_data;
- if (test_bit(GFF_EXLOCK, &gf->f_flags))
- goto skip_lock;
- }
- gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
- LM_FLAG_TRY_1CB|GL_ATIME, &gh);
- do_unlock = 1;
- ret = gfs2_glock_nq_atime(&gh);
- if (ret == GLR_TRYFAILED)
- goto out_noerror;
- if (unlikely(ret))
- goto out_unlock;
- }
-skip_lock:
+ int ret;
+
+ gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
+ ret = gfs2_glock_nq_atime(&gh);
+ if (unlikely(ret))
+ goto out_uninit;
if (!gfs2_is_stuffed(ip))
ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
-
- if (do_unlock) {
- gfs2_glock_dq_m(1, &gh);
- gfs2_holder_uninit(&gh);
- }
-out:
+ gfs2_glock_dq(&gh);
+out_uninit:
+ gfs2_holder_uninit(&gh);
if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
ret = -EIO;
return ret;
-out_noerror:
- ret = 0;
-out_unlock:
- if (do_unlock)
- gfs2_holder_uninit(&gh);
- goto out;
}
/**
projects / deliverable / linux.git / blobdiff