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    Subject[PATCH 03/12] BKL: Remove BKL from isofs
    Date
    As in other file systems, we can replace the big kernel lock
    with {un,}lock_super in isofs. This means we can now access
    multiple file systems concurrently, but it also means that
    we serialize readdir and lookup across sleeping operations
    which previously released the big kernel lock. This should
    not matter though, as these operations are in practice
    serialized through the hardware access.

    The isofs_get_blocks functions now does not take any lock
    any more, it used to recursively get the BKL. After looking
    at the code for hours, I convinced myself that it was never
    needed here anyway, because it only reads constant fields
    of the inode and writes to a buffer head array that is
    at this time only visible to the caller.

    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    ---
    fs/isofs/dir.c | 6 +++---
    fs/isofs/inode.c | 16 ++++++----------
    fs/isofs/namei.c | 8 ++++----
    fs/isofs/rock.c | 8 ++++----
    4 files changed, 17 insertions(+), 21 deletions(-)

    diff --git a/fs/isofs/dir.c b/fs/isofs/dir.c
    index e0aca9a..4e6c000 100644
    --- a/fs/isofs/dir.c
    +++ b/fs/isofs/dir.c
    @@ -10,7 +10,6 @@
    *
    * isofs directory handling functions
    */
    -#include <linux/smp_lock.h>
    #include <linux/gfp.h>
    #include "isofs.h"

    @@ -255,18 +254,19 @@ static int isofs_readdir(struct file *filp,
    char *tmpname;
    struct iso_directory_record *tmpde;
    struct inode *inode = filp->f_path.dentry->d_inode;
    + struct super_block *sb = inode->i_sb;

    tmpname = (char *)__get_free_page(GFP_KERNEL);
    if (tmpname == NULL)
    return -ENOMEM;

    - lock_kernel();
    + lock_super(sb);
    tmpde = (struct iso_directory_record *) (tmpname+1024);

    result = do_isofs_readdir(inode, filp, dirent, filldir, tmpname, tmpde);

    free_page((unsigned long) tmpname);
    - unlock_kernel();
    + unlock_super(sb);
    return result;
    }

    diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
    index 05baf77..57209f1 100644
    --- a/fs/isofs/inode.c
    +++ b/fs/isofs/inode.c
    @@ -17,7 +17,6 @@
    #include <linux/slab.h>
    #include <linux/nls.h>
    #include <linux/ctype.h>
    -#include <linux/smp_lock.h>
    #include <linux/statfs.h>
    #include <linux/cdrom.h>
    #include <linux/parser.h>
    @@ -44,11 +43,11 @@ static void isofs_put_super(struct super_block *sb)
    struct isofs_sb_info *sbi = ISOFS_SB(sb);

    #ifdef CONFIG_JOLIET
    - lock_kernel();
    + lock_super(sb);

    unload_nls(sbi->s_nls_iocharset);

    - unlock_kernel();
    + unlock_super(sb);
    #endif

    kfree(sbi);
    @@ -571,13 +570,13 @@ static int isofs_fill_super(struct super_block *s, void *data, int silent)
    int table, error = -EINVAL;
    unsigned int vol_desc_start;

    - lock_kernel();
    + lock_super(s);

    save_mount_options(s, data);

    sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
    if (!sbi) {
    - unlock_kernel();
    + unlock_super(s);
    return -ENOMEM;
    }
    s->s_fs_info = sbi;
    @@ -904,7 +903,7 @@ root_found:

    kfree(opt.iocharset);

    - unlock_kernel();
    + unlock_super(s);
    return 0;

    /*
    @@ -942,9 +941,9 @@ out_freebh:
    brelse(bh);
    out_freesbi:
    kfree(opt.iocharset);
    + unlock_super(s);
    kfree(sbi);
    s->s_fs_info = NULL;
    - unlock_kernel();
    return error;
    }

    @@ -983,8 +982,6 @@ int isofs_get_blocks(struct inode *inode, sector_t iblock_s,
    int section, rv, error;
    struct iso_inode_info *ei = ISOFS_I(inode);

    - lock_kernel();
    -
    error = -EIO;
    rv = 0;
    if (iblock < 0 || iblock != iblock_s) {
    @@ -1060,7 +1057,6 @@ int isofs_get_blocks(struct inode *inode, sector_t iblock_s,

    error = 0;
    abort:
    - unlock_kernel();
    return rv != 0 ? rv : error;
    }

    diff --git a/fs/isofs/namei.c b/fs/isofs/namei.c
    index ab438be..cf67973 100644
    --- a/fs/isofs/namei.c
    +++ b/fs/isofs/namei.c
    @@ -6,7 +6,6 @@
    * (C) 1991 Linus Torvalds - minix filesystem
    */

    -#include <linux/smp_lock.h>
    #include <linux/gfp.h>
    #include "isofs.h"

    @@ -168,6 +167,7 @@ struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, struct nam
    int found;
    unsigned long uninitialized_var(block);
    unsigned long uninitialized_var(offset);
    + struct super_block *sb = dir->i_sb;
    struct inode *inode;
    struct page *page;

    @@ -177,7 +177,7 @@ struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, struct nam
    if (!page)
    return ERR_PTR(-ENOMEM);

    - lock_kernel();
    + lock_super(sb);
    found = isofs_find_entry(dir, dentry,
    &block, &offset,
    page_address(page),
    @@ -188,10 +188,10 @@ struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, struct nam
    if (found) {
    inode = isofs_iget(dir->i_sb, block, offset);
    if (IS_ERR(inode)) {
    - unlock_kernel();
    + unlock_super(sb);
    return ERR_CAST(inode);
    }
    }
    - unlock_kernel();
    + unlock_super(sb);
    return d_splice_alias(inode, dentry);
    }
    diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c
    index 96a685c..0599c65 100644
    --- a/fs/isofs/rock.c
    +++ b/fs/isofs/rock.c
    @@ -8,7 +8,6 @@

    #include <linux/slab.h>
    #include <linux/pagemap.h>
    -#include <linux/smp_lock.h>

    #include "isofs.h"
    #include "rock.h"
    @@ -661,6 +660,7 @@ static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
    {
    struct inode *inode = page->mapping->host;
    struct iso_inode_info *ei = ISOFS_I(inode);
    + struct super_block *sb = inode->i_sb;
    char *link = kmap(page);
    unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
    struct buffer_head *bh;
    @@ -678,7 +678,7 @@ static int rock_ridge_symlink_readpage(struct file *file, struct page *page)

    init_rock_state(&rs, inode);
    block = ei->i_iget5_block;
    - lock_kernel();
    + lock_super(sb);
    bh = sb_bread(inode->i_sb, block);
    if (!bh)
    goto out_noread;
    @@ -748,7 +748,7 @@ repeat:
    goto fail;
    brelse(bh);
    *rpnt = '\0';
    - unlock_kernel();
    + unlock_super(sb);
    SetPageUptodate(page);
    kunmap(page);
    unlock_page(page);
    @@ -765,7 +765,7 @@ out_bad_span:
    printk("symlink spans iso9660 blocks\n");
    fail:
    brelse(bh);
    - unlock_kernel();
    + unlock_super(sb);
    error:
    SetPageError(page);
    kunmap(page);
    --
    1.7.1


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