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NTFS: Change ntfs_attr_find_vcn_nolock() to also take an optional attribute

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search context as argument.  This allows calling it with the mft
      record mapped.  Update all callers.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
This commit is contained in:
Anton Altaparmakov
2005-10-04 14:01:14 +01:00
parent fd9d63678d
commit 69b41e3c02
5 changed files with 59 additions and 44 deletions
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84
fs/ntfs/attrib.c
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@@ -406,9 +406,9 @@ retry_remap:
/**
* ntfs_attr_find_vcn_nolock - find a vcn in the runlist of an ntfs inode
* @ni: ntfs inode describing the runlist to search
* @vcn: vcn to find
* @write_locked: true if the runlist is locked for writing
* @ni: ntfs inode describing the runlist to search
* @vcn: vcn to find
* @ctx: active attribute search context if present or NULL if not
*
* Find the virtual cluster number @vcn in the runlist described by the ntfs
* inode @ni and return the address of the runlist element containing the @vcn.
@@ -416,9 +416,22 @@ retry_remap:
* If the @vcn is not mapped yet, the attempt is made to map the attribute
* extent containing the @vcn and the vcn to lcn conversion is retried.
*
* If @write_locked is true the caller has locked the runlist for writing and
* if false for reading.
* If @ctx is specified, it is an active search context of @ni and its base mft
* record. This is needed when ntfs_attr_find_vcn_nolock() encounters unmapped
* runlist fragments and allows their mapping. If you do not have the mft
* record mapped, you can specify @ctx as NULL and ntfs_attr_find_vcn_nolock()
* will perform the necessary mapping and unmapping.
*
* Note, ntfs_attr_find_vcn_nolock() saves the state of @ctx on entry and
* restores it before returning. Thus, @ctx will be left pointing to the same
* attribute on return as on entry. However, the actual pointers in @ctx may
* point to different memory locations on return, so you must remember to reset
* any cached pointers from the @ctx, i.e. after the call to
* ntfs_attr_find_vcn_nolock(), you will probably want to do:
* m = ctx->mrec;
* a = ctx->attr;
* Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
* you cache ctx->mrec in a variable @m of type MFT_RECORD *.
* Note you need to distinguish between the lcn of the returned runlist element
* being >= 0 and LCN_HOLE. In the later case you have to return zeroes on
* read and allocate clusters on write.
@@ -433,22 +446,31 @@ retry_remap:
* -ENOMEM - Not enough memory to map runlist.
* -EIO - Critical error (runlist/file is corrupt, i/o error, etc).
*
* Locking: - The runlist must be locked on entry and is left locked on return.
* - If @write_locked is FALSE, i.e. the runlist is locked for reading,
* the lock may be dropped inside the function so you cannot rely on
* the runlist still being the same when this function returns.
* WARNING: If @ctx is supplied, regardless of whether success or failure is
* returned, you need to check IS_ERR(@ctx->mrec) and if TRUE the @ctx
* is no longer valid, i.e. you need to either call
* ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
* In that case PTR_ERR(@ctx->mrec) will give you the error code for
* why the mapping of the old inode failed.
*
* Locking: - The runlist described by @ni must be locked for writing on entry
* and is locked on return. Note the runlist may be modified when
* needed runlist fragments need to be mapped.
* - If @ctx is NULL, the base mft record of @ni must not be mapped on
* entry and it will be left unmapped on return.
* - If @ctx is not NULL, the base mft record must be mapped on entry
* and it will be left mapped on return.
*/
runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
const BOOL write_locked)
ntfs_attr_search_ctx *ctx)
{
unsigned long flags;
runlist_element *rl;
int err = 0;
BOOL is_retry = FALSE;
ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
ni->mft_no, (unsigned long long)vcn,
write_locked ? "write" : "read");
ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, with%s ctx.",
ni->mft_no, (unsigned long long)vcn, ctx ? "" : "out");
BUG_ON(!ni);
BUG_ON(!NInoNonResident(ni));
BUG_ON(vcn < 0);
@@ -482,33 +504,22 @@ retry_remap:
}
if (!err && !is_retry) {
/*
* The @vcn is in an unmapped region, map the runlist and
* retry.
* If the search context is invalid we cannot map the unmapped
* region.
*/
if (!write_locked) {
up_read(&ni->runlist.lock);
down_write(&ni->runlist.lock);
if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
LCN_RL_NOT_MAPPED)) {
up_write(&ni->runlist.lock);
down_read(&ni->runlist.lock);
if (IS_ERR(ctx->mrec))
err = PTR_ERR(ctx->mrec);
else {
/*
* The @vcn is in an unmapped region, map the runlist
* and retry.
*/
err = ntfs_map_runlist_nolock(ni, vcn, ctx);
if (likely(!err)) {
is_retry = TRUE;
goto retry_remap;
}
}
err = ntfs_map_runlist_nolock(ni, vcn, NULL);
if (!write_locked) {
up_write(&ni->runlist.lock);
down_read(&ni->runlist.lock);
}
if (likely(!err)) {
is_retry = TRUE;
goto retry_remap;
}
/*
* -EINVAL coming from a failed mapping attempt is equivalent
* to i/o error for us as it should not happen in our code
* paths.
*/
if (err == -EINVAL)
err = -EIO;
} else if (!err)
@@ -1181,6 +1192,7 @@ int ntfs_attr_lookup(const ATTR_TYPE type, const ntfschar *name,
ntfs_inode *base_ni;
ntfs_debug("Entering.");
BUG_ON(IS_ERR(ctx->mrec));
if (ctx->base_ntfs_ino)
base_ni = ctx->base_ntfs_ino;
else