[GFS2] Fix lock ordering bug in page fault path

Mmapped files were able to trigger a lock ordering bug. Private
maps do not need to take the glock so early on. Shared maps do
unfortunately, however we can get around that by adding a flag
into the flags for the struct gfs2_file. This only works because
we are taking an exclusive lock at this point, so we know that
nobody else can be racing with us.

Fixes Red Hat bugzilla: #201196

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse 2006-08-04 15:41:22 -04:00
parent 899bb26450
commit 59a1cc6bda
5 changed files with 32 additions and 25 deletions

View file

@ -279,6 +279,7 @@ static inline struct gfs2_sbd *GFS2_SB(struct inode *inode)
enum {
GFF_DID_DIRECT_ALLOC = 0,
GFF_EXLOCK = 1,
};
struct gfs2_file {

View file

@ -256,8 +256,8 @@ static unsigned int current_tail(struct gfs2_sbd *sdp)
if (list_empty(&sdp->sd_ail1_list))
tail = sdp->sd_log_head;
else {
ai = list_entry(sdp->sd_ail1_list.prev,
struct gfs2_ail, ai_list);
ai = list_entry(sdp->sd_ail1_list.prev, struct gfs2_ail,
ai_list);
tail = ai->ai_first;
}

View file

@ -237,14 +237,22 @@ static int gfs2_readpage(struct file *file, struct page *page)
struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
struct gfs2_holder gh;
int error;
int do_unlock = 0;
if (likely(file != &gfs2_internal_file_sentinal)) {
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, GL_ATIME|GL_AOP, &gh);
do_unlock = 1;
error = gfs2_glock_nq_m_atime(1, &gh);
if (unlikely(error))
goto out_unlock;
}
skip_lock:
if (gfs2_is_stuffed(ip)) {
error = stuffed_readpage(ip, page);
unlock_page(page);
@ -262,7 +270,7 @@ static int gfs2_readpage(struct file *file, struct page *page)
return error;
out_unlock:
unlock_page(page);
if (file != &gfs2_internal_file_sentinal)
if (do_unlock)
gfs2_holder_uninit(&gh);
goto out;
}
@ -291,17 +299,24 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping,
struct gfs2_holder gh;
unsigned page_idx;
int ret;
int do_unlock = 0;
if (likely(file != &gfs2_internal_file_sentinal)) {
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|GL_AOP, &gh);
do_unlock = 1;
ret = gfs2_glock_nq_m_atime(1, &gh);
if (ret == GLR_TRYFAILED)
goto out_noerror;
if (unlikely(ret))
goto out_unlock;
}
skip_lock:
if (gfs2_is_stuffed(ip)) {
struct pagevec lru_pvec;
pagevec_init(&lru_pvec, 0);
@ -326,7 +341,7 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping,
ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
}
if (likely(file != &gfs2_internal_file_sentinal)) {
if (do_unlock) {
gfs2_glock_dq_m(1, &gh);
gfs2_holder_uninit(&gh);
}
@ -344,7 +359,7 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping,
unlock_page(page);
page_cache_release(page);
}
if (likely(file != &gfs2_internal_file_sentinal))
if (do_unlock)
gfs2_holder_uninit(&gh);
goto out;
}

View file

@ -46,13 +46,7 @@ static struct page *gfs2_private_nopage(struct vm_area_struct *area,
unsigned long address, int *type)
{
struct gfs2_inode *ip = GFS2_I(area->vm_file->f_mapping->host);
struct gfs2_holder i_gh;
struct page *result;
int error;
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &i_gh);
if (error)
return NULL;
set_bit(GIF_PAGED, &ip->i_flags);
@ -61,8 +55,6 @@ static struct page *gfs2_private_nopage(struct vm_area_struct *area,
if (result && result != NOPAGE_OOM)
pfault_be_greedy(ip);
gfs2_glock_dq_uninit(&i_gh);
return result;
}
@ -141,7 +133,9 @@ static int alloc_page_backing(struct gfs2_inode *ip, struct page *page)
static struct page *gfs2_sharewrite_nopage(struct vm_area_struct *area,
unsigned long address, int *type)
{
struct gfs2_inode *ip = GFS2_I(area->vm_file->f_mapping->host);
struct file *file = area->vm_file;
struct gfs2_file *gf = file->private_data;
struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
struct gfs2_holder i_gh;
struct page *result = NULL;
unsigned long index = ((address - area->vm_start) >> PAGE_CACHE_SHIFT) +
@ -156,13 +150,14 @@ static struct page *gfs2_sharewrite_nopage(struct vm_area_struct *area,
set_bit(GIF_PAGED, &ip->i_flags);
set_bit(GIF_SW_PAGED, &ip->i_flags);
error = gfs2_write_alloc_required(ip,
(uint64_t)index << PAGE_CACHE_SHIFT,
error = gfs2_write_alloc_required(ip, (u64)index << PAGE_CACHE_SHIFT,
PAGE_CACHE_SIZE, &alloc_required);
if (error)
goto out;
set_bit(GFF_EXLOCK, &gf->f_flags);
result = filemap_nopage(area, address, type);
clear_bit(GFF_EXLOCK, &gf->f_flags);
if (!result || result == NOPAGE_OOM)
goto out;
@ -177,8 +172,7 @@ static struct page *gfs2_sharewrite_nopage(struct vm_area_struct *area,
}
pfault_be_greedy(ip);
out:
out:
gfs2_glock_dq_uninit(&i_gh);
return result;

View file

@ -153,8 +153,7 @@ static int get_log_header(struct gfs2_jdesc *jd, unsigned int blk,
if (lh.lh_header.mh_magic != GFS2_MAGIC ||
lh.lh_header.mh_type != GFS2_METATYPE_LH ||
lh.lh_blkno != blk ||
lh.lh_hash != hash)
lh.lh_blkno != blk || lh.lh_hash != hash)
return 1;
*head = lh;
@ -482,11 +481,9 @@ int gfs2_recover_journal(struct gfs2_jdesc *jd)
/* Acquire a shared hold on the transaction lock */
error = gfs2_glock_nq_init(sdp->sd_trans_gl,
LM_ST_SHARED,
error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED,
LM_FLAG_NOEXP | LM_FLAG_PRIORITY |
GL_NOCANCEL | GL_NOCACHE,
&t_gh);
GL_NOCANCEL | GL_NOCACHE, &t_gh);
if (error)
goto fail_gunlock_ji;