From 51ff87bdd9f21a5d3672517b75d25ab5842d94a8 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Mon, 15 Oct 2007 14:42:35 +0100 Subject: [GFS2] Clean up internal read function As requested by Christoph, this patch cleans up GFS2's internal read function so that it no longer uses the do_generic_mapping_read function. This function is obsolete and GFS2 is the last user of it. As a side effect the internal read code gets smaller and easier to read and gfs2_readpage is split into two. One function has the locking and the other function has the rest of the logic. Signed-off-by: Steven Whitehouse Cc: Christoph Hellwig --- fs/gfs2/ops_address.c | 151 +++++++++++++++++++++++++++++++++----------------- 1 file changed, 101 insertions(+), 50 deletions(-) (limited to 'fs/gfs2/ops_address.c') diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c index 9679f8b9870d..9bb24b1d9c05 100644 --- a/fs/gfs2/ops_address.c +++ b/fs/gfs2/ops_address.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "gfs2.h" #include "incore.h" @@ -32,7 +33,6 @@ #include "quota.h" #include "trans.h" #include "rgrp.h" -#include "ops_file.h" #include "super.h" #include "util.h" #include "glops.h" @@ -231,62 +231,115 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page) /** - * 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. If the GFF_EXLOCK flags is set + * then we already hold the glock (due to page fault) and thus we call + * __gfs2_readpage() directly. Otherwise 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; + + if (file) { + struct gfs2_file *gf = file->private_data; + if (test_bit(GFF_EXLOCK, &gf->f_flags)) + return __gfs2_readpage(file, page); } + + 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; } /** @@ -314,21 +367,19 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping, 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; + 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: if (!gfs2_is_stuffed(ip)) ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block); -- cgit v1.2.3