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authorHugh Dickins <hugh@veritas.com>2008-02-04 22:28:44 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:15 -0800
commitd3602444e1e3485890eea5f61366e19a287c00c4 (patch)
treef27cca0ce7c113c6b8f15f77abc3124faea9e2c8 /mm/shmem.c
parent27d54b398ec0edea0e7417f003171017300e0efc (diff)
shmem_getpage return page locked
In the new aops, write_begin is supposed to return the page locked: though I've seen no ill effects, that's been overlooked in the case of shmem_write_begin, and should be fixed. Then shmem_write_end must unlock the page: do so _after_ updating i_size, as we found to be important in other filesystems (though since shmem pages don't go the usual writeback route, they never suffered from that corruption). For shmem_write_begin to return the page locked, we need shmem_getpage to return the page locked in SGP_WRITE case as well as SGP_CACHE case: let's simplify the interface and return it locked even when SGP_READ. Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c22
1 files changed, 13 insertions, 9 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 20cefe16eaf..43d071922b8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -729,6 +729,8 @@ static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
(void) shmem_getpage(inode,
attr->ia_size>>PAGE_CACHE_SHIFT,
&page, SGP_READ, NULL);
+ if (page)
+ unlock_page(page);
}
/*
* Reset SHMEM_PAGEIN flag so that shmem_truncate can
@@ -1286,12 +1288,7 @@ repeat:
SetPageUptodate(filepage);
}
done:
- if (*pagep != filepage) {
- *pagep = filepage;
- if (sgp != SGP_CACHE)
- unlock_page(filepage);
-
- }
+ *pagep = filepage;
return 0;
failed:
@@ -1469,12 +1466,13 @@ shmem_write_end(struct file *file, struct address_space *mapping,
{
struct inode *inode = mapping->host;
+ if (pos + copied > inode->i_size)
+ i_size_write(inode, pos + copied);
+
+ unlock_page(page);
set_page_dirty(page);
page_cache_release(page);
- if (pos+copied > inode->i_size)
- i_size_write(inode, pos+copied);
-
return copied;
}
@@ -1529,6 +1527,7 @@ shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t
if (err)
break;
+ unlock_page(page);
left = bytes;
if (PageHighMem(page)) {
volatile unsigned char dummy;
@@ -1610,6 +1609,8 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
desc->error = 0;
break;
}
+ if (page)
+ unlock_page(page);
/*
* We must evaluate after, since reads (unlike writes)
@@ -1899,6 +1900,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
iput(inode);
return error;
}
+ unlock_page(page);
inode->i_op = &shmem_symlink_inode_operations;
kaddr = kmap_atomic(page, KM_USER0);
memcpy(kaddr, symname, len);
@@ -1926,6 +1928,8 @@ static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
struct page *page = NULL;
int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
+ if (page)
+ unlock_page(page);
return page;
}